Given the task definition and input, reply with output. You are given a paragraph, a question and some answer options (associated with "A", "B", "C", "D", etc.) You need to list all the correct answer options with their associated letters (e.g. "A" can be a valid answer). Note that sometimes, more than one option can answer the question correctly and completely. In those cases, please generate all such options separated by a comma (e.g. "A, B" is a valid answer). Do not generate anything else apart from one or more of the following characters: 'A', 'B, 'C', 'D', etc.

Paragraph- Sent 1: An atom is the very smallest particle that still the elements properties.
Sent 2: All the atoms of an element are alike.
Sent 3: They are also different from the atoms of all other elements.
Sent 4: For example, atoms of gold are always the same.
Sent 5: It does not matter if they are found in a gold nugget or a gold ring.
Sent 6: All gold atoms have the same structure and properties.
Sent 7: For example, all gold atoms contain 79 protons.
Sent 8: One of golds unique properties is that it is a great conductor of electricity.
Sent 9: Gold is a better conductor of electricity than copper.
Sent 10: Gold is more rare and expensive than copper.
Sent 11: Copper is used in house wiring.
Sent 12: Gold is far too expensive. 
Question: How could we describe the atoms of an element? (A) They are the smallest particles of an element. All the atoms of an element are alike and are also different from the atoms of all other elements (B) The very smallest particle that still the elements properties (C) What makes up an element (D) All atoms of an element are alike (E) All atoms of an element are different.

A, B, D.