In this task, you will be presented with a context passage, a question about that paragraph, and a possible answer to that question. The task is to check the validity of the answer. Answer with "Yes" or "No".

Q: Fossils can be used to match up rock layers. As organisms change over time, they look different. Older fossils will look different than younger fossils. Some organisms only survived for a short time before going extinct. Knowing what organisms looked like at certain times also helps date rock layers. Some fossils are better than others for this use. The fossils that are very distinct at certain times of Earths history are called index fossils. Index fossils are commonly used to match rock layers. You can see how this works in Figure 2.30. If two rock layers have the same index fossils, then they're probably about the same age. <sep>What kind of fossils are used to date rock layers?<sep>Index fossils

A: Yes
****
Q: The day was just breaking, as I left the tower; though it was still too dark in the house to be able to see without a light, and I took one of the study candles with me on my 'round.  By the time I had finished the ground floor, the daylight was creeping in, wanly, through the barred windows.  My search had shown me nothing fresh.  Everything appeared to be in order, and I was on the point of extinguishing my candle, when the thought suggested itself to me to have another glance 'round the cellars.  I had not, if I remember rightly, been into them since my hasty search on the evening of the attack.  For, perhaps, the half of a minute, I hesitated.  I would have been very willing to forego the task--as, indeed, I am inclined to think any man well might--for of all the great, awe-inspiring rooms in this house, the cellars are the hugest and weirdest.  Great, gloomy caverns of places, unlit by any ray of daylight.  Yet, I would not shirk the work.  I felt that to do so would smack of sheer cowardice.  Besides, as I reassured myself, the cellars were really the most unlikely places in which to come across anything dangerous; considering that they can be entered, only through a heavy oaken door, the key of which, I carry always on my person. <sep>When did the person consider extinguishing the candle?<sep>Found nothing

A: Yes
****
Q: Water flowing over Earths surface or underground causes erosion and deposition. Water flowing over a steeper slope moves faster and causes more erosion. How water transports particles depends on their size. When water slows down, it starts depositing sediment. This process starts with the largest particles first. Runoff erodes the land after a heavy rain. It picks up sediment. Runoff carries most of the sediment to bodies of water. Mountain streams erode narrow, V-shaped valleys and waterfalls. Erosion and deposition by slow-flowing rivers create broad floodplains and meanders. Deposition by streams and rivers may form alluvial fans and deltas. Floodwaters may deposit natural levees. Erosion and deposition by groundwater can form caves and sinkholes. Stalactites and stalagmites are mineral deposits. They build up in caves as water continues to drip. <sep>What picks up sediment after a heavy rain?<sep>Runoff

A:
Yes
****
