You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) the answer is unique, (iv) its answer is a continous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage 

"story": "Traditionally considered the last part of the Stone Age, the Neolithic followed the terminal Holocene Epipaleolithic period and commenced with the beginning of farming, which produced the "Neolithic Revolution". It ended when metal tools became widespread (in the Copper Age or Bronze Age; or, in some geographical regions, in the Iron Age). The Neolithic is a progression of behavioral and cultural characteristics and changes, including the use of wild and domestic crops and of domesticated animals. 

The beginning of the Neolithic culture is considered to be in the Levant (Jericho, modern-day West Bank) about 10,200 – 8,800 BC. It developed directly from the Epipaleolithic Natufian culture in the region, whose people pioneered the use of wild cereals, which then evolved into true farming. The Natufian period was between 12,000 and 10,200 BC, and the so-called "proto-Neolithic" is now included in the Pre-Pottery Neolithic (PPNA) between 10,200 and 8,800 BC. As the Natufians had become dependent on wild cereals in their diet, and a sedentary way of life had begun among them, the climatic changes associated with the Younger Dryas are thought to have forced people to develop farming."
Solution: What did Neolithic follow?
Why? This question is based on the following sentence in the passage - the Neolithic followed the terminal Holocene Epipaleolithic period and this is answerable from the passage. So, it is a good question.

New input: CHAPTER XXVII. LEONARD DE CARTIENNE. 

We all three stood and looked at one another for a moment, Milly Hart with her finger still pointing to the vacant place where the photograph had been. Then Cecil broke into a short laugh. 

"We're looking very tragical about it," he said lightly. "Mysterious joint disappearance of Leonard de Cartienne and a photograph of Mr. Hart. Now, if it had been a photograph of a pretty girl instead of a middle-aged man, we might have connected the two. Hallo!" 

He broke off in his speech and turned round. Standing in the doorway, looking at us, was Leonard de Cartienne, with a slight smile on his thin lips. 

"Behold the missing link--I mean man!" exclaimed Cecil. "Good old Leonard! Do you know, you gave us quite a fright. We expected to find you here and the room was empty. Are you better?" 

"Yes, thanks! I'm all right now," he answered. "I've been out in the yard and had a blow. What's Milly looking so scared about? And what was it I heard you say about a photograph?" 

"Father's likeness has gone," she explained, turning round with tears in her eyes. "It was there on the mantelpiece this afternoon and now, when we came in to look at it, it has gone!" 

"I should think that, if it really has disappeared," de Cartienne remarked incredulously, "the servant must have moved it. Ask her." 

Miss Hart rang the bell and in the meantime we looked about the room. It was all in vain. We could find no trace of it, nor could the servant who answered the summons give us any information. She had seen it in its usual place early in the morning when she had been dusting. Since then she had not entered the room. 
Solution:
Who started laughing?