Given a scientific passage and an answer, generate a question for the given answer.

Example input: Passage: A frameshift mutation is a deletion or insertion of one or more nucleotides that changes the reading frame of the base sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in RNA:. Answer: nucleotides.
Example output: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Example explanation: The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.
Q: Passage: The structure of a chloroplast is shown in Figure below . The chloroplast is surrounded by two membranes. Inside the chloroplast are stacks of flattened sacs of membrane, called thylakoids . The thylakoids contain chlorophyll. Surrounding the thylakoids is a space called the stroma . The stroma is filled with watery ("aqueous") fluid. Answer: chlorophyll
A:
Thylakoids in a chloroplast contain what plant pigment?