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: Renewable resources can be renewed as they are used.
Sent 2: An example is timber, which comes from trees.
Sent 3: New trees can be planted to replace those that are cut down.
Sent 4: Sunlight is a renewable resource.
Sent 5: It seems we will never run out of that!
Sent 6: Just because a resource is renewable, it doesnt mean we should use it carelessly.
Sent 7: If we  aren't careful, we can pollute resources.
Sent 8: Then they may no longer be fit for use.
Sent 9: Water is one example.
Sent 10: If we pollute a water source it may not be usable for drinking, bathing, or any other type of use.
Sent 11: We can also overuse resources that should be renewable.
Sent 12: In this case, the resources may not be able to recover.
Sent 13: For example, fish are renewable resources.
Sent 14: Thats because they can reproduce and make more fish.
Sent 15: But water pollution and overfishing can cause them to die out if their population becomes too low.
Sent 16: Figure 2.16 shows another example. 
Question: What renewable resource can be replanted? (A) Timber (B) New trees can be planted to replace those that are cut down (C) Trees (D) Fish.

Solution: A, B, C.