You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
Given a scientific passage and an answer, generate a question for the given answer.

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.
Solution: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Why? The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.

New input: Passage: For decades Pluto was a planet. But even then, scientists knew it was an unusual planet. The other outer planets are all gas giants. Pluto is small, icy and rocky. With a diameter of about 2400 kilometers, it has only about 1/5 the mass of Earth's Moon. The other planets orbit in a plane. Pluto's orbit is tilted. The shape of the orbit is like a long, narrow ellipse. Pluto's orbit is so elliptical that sometimes it is inside the orbit of Neptune. Answer: neptune
Solution:
Pluto's orbit is so elliptical that sometimes it is inside the orbit of which planet?