IMO C

please explain why.

Mclaughlin wrote:please explain why.

Ok let us break the sentence into part and then fit in the options.

Original sentence is

Because Halley’s comet changes orbit slightly during the seventy-six-year interval between passing close to Earth, it may veer onto a collision course with a planet sometime in the distant future.

The sentence structure is
Because....(reason part)......,(Effect part starting with 'it').

Now conc on the reason part.
Because Halley’s comet changes orbit slightly during the seventy-six-year interval... the sentence must now modify(or tell something about) the time interval i.e it should answer the question, which 76 year period?
And also fit in with the remaining part "close to Earth"

keeping the above in mind plug in the options.. u shud get it, if not let me know which option u find difficult to eliminate and we can discuss.

Hi guys,

I'm a bit confused by the use of 'its', Is it correct in this tense?
If the answer is a BIG yes, could you explain why?
(pronoun error is one of my weak points )