NASA recently published a report cautioning that many of the

There are two major problems with the original sentence: (split is much - many / pose - poses)
1. Much vs many : Debries = uncountable = much (such as so much money vs so many dollars where money is uncountable and dollars is countable )
2.Subject verb agreement: pose vs poses Much debris is a singular subject and fits with poses.

NASA recently published a report cautioning that many of the space debris to which satellites and spacefaring vessels are exposed pose a significant risk of damaging or destroying satellites and vessels in instances of accidental impact.

A: many of the space debris to which satellites and spacefaring vessels are exposed pose - out due to error 1
B: many of the space debris that satellites and spacefaring vessels are exposed to poses - out due to error 1 & 2 many - plural => pose
C: many of the debris that is in space and that satellites and spacefaring vessels are exposed to pose - out due to error 1
D: much of the debris that is in space and satellites and spacefaring vessels are exposed to poses -wordy construction. No need to classify derbies
E: much of the space debris to which satellites and spacefaring vessels are exposed poses - correct option.
Answer - E

Exposed to pose/poses is incorrect usage,hence eliminate b,c,d.Between a and e,E because of correct tense and the usage of poses.

Its against Much of the debris vs many of the debris---
as we cannot count debris it should be much of the debris
as much of debris is singular the verb should be poses

we are left with D and E. D is wrong as satellites and spacefaring vessels are exposed to this is modifying nothing

E is perfect

core sentence:
debris poses risk
debris is non-countable , so we use "much". Eliminate A,B and C
D distort the meaning by saying the debris, the satellite and the vessels are exposed
E- correct

E for me.

much of the space debris is correct. Also "much of the space debris" is singular.

Use of 'many' rules out A, B and C.
D is awkward
E is the right Ans

Posted from my mobile device

Answer must be (D) for the highlighted errors in the given options.

NASA recently published a report cautioning that many of the space debris to which satellites and spacefaring vessels are exposed pose a significant risk of damaging or destroying satellites and vessels in instances of accidental impact.

A: many of the space debris to which satellites and spacefaring vessels are exposed pose -> space debris is uncountable, so "many" is incorrect to use. Incorrect.
B: many of the space debris that satellites and spacefaring vessels are exposed to poses -> Same as A. Incorrect.
C: many of the debris that is in space and that satellites and spacefaring vessels are exposed to pose -> Same as A. Incorrect.
D: much of the debris that is in space and satellites and spacefaring vessels are exposed to poses -> " debris that is in space" can be said as "space debris". Incorrect.
E: much of the space debris to which satellites and spacefaring vessels are exposed poses -> It is better. Let's keep it.

So, I think E.