Given a scientific passage and an answer, generate a question for the given answer.
One example is below.
Q: 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.
A: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Rationale: The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.
Q: Passage: A front forms at the boundary between two air masses. Types of fronts include cold, warm, occluded, and stationary fronts. Clouds, precipitation, and storms commonly occur along fronts. Answer: a front
A:
What forms at the boundary between two air masses?