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.
Example: Paragraph- Sent 1: Obama was born on August 4, 1961, at Kapiʻolani Maternity & Gynecological Hospital in Honolulu, Hawaii.
Sent 2: He is the only President to have been born in Hawaii.
Sent 3: He was born to a white mother and a black father.
Sent 4: His mother, Ann Dunham (1942-1995), was born in Wichita, Kansas, of mostly English descent, with some German, Irish, Scottish, Swiss, and Welsh ancestry. Question: How old was Obama's mother when he was born? (A) teenager (B) in his 40s (C) mid 20s (D) almost twenty.
Example solution: D.
Example explanation: Obama was born in 1961. His mother was born in 1942 and 1961-1942=19. Therefore, "almost twenty" answers the question sufficiently.

Problem: Paragraph- Sent 1: If you build a campfire, you start with a large stack of sticks and logs.
Sent 2: As the fire burns, the stack slowly shrinks.
Sent 3: By the end of the evening, all that is left is a small pile of ashes.
Sent 4: What happened to the matter that you started with?
Sent 5: Was it destroyed by the flames?
Sent 6: It may seem that way.
Sent 7: What do you think happened?
Sent 8: The truth is that the same amount of matter still exists.
Sent 9: The wood changed not only to ashes, but also to carbon dioxide, water vapor, and other gases.
Sent 10: The gases floated off into the air, leaving behind just the ashes.
Sent 11: Although matter was changed, it was not created or destroyed.
Sent 12: Because the same amount of matter still exists, we can say that matter is conserved.
Sent 13: You may wonder how it can be conserved if something is now missing?
Sent 14: Assume you had measured the mass of the wood before you burned it.
Sent 15: Assume you had also trapped the gases released by the burning wood and measured their mass and the mass of the ashes.
Sent 16: What would you find?
Sent 17: The ashes and gases combined have the same mass as the wood you started with.
Sent 18: This example illustrates the law of conservation of mass. 
Question: What happens to sticks and logs in a campfire? (A) They change into pile of ashes (B) They are permanently eliminated from the earth (C) As the fire burns, the stack slowly shrinks and a while later, all that is left is a small pile of ashes (D) They get converted to fire and heat (E) They are converted to ashes and gases.

Solution: A, C, E.