[PowerPrep Spoiler]Pls help with text completion

CAN SOMEONE PLS HELP WITH THIS TEXT COMPLETION

The highlighted answer is not necessarily the answer.

add spoiler when asking pp or pp+ questions

I might be wrong.

look at the 'but" dividing both sentences. The blank is on the side.
So the right sentence must be contrasted with the left sentence.

First sentence says there is little risk of collision , meaning its safe.
So contrasting that

safe - but - less/not safe .
So the second idea must be something negative.
the orbital environment in future is likely to be less safe.

by POE all the answers except protected, benign can be eliminated.

I am stuck in between these two answer choices. However, I THINK orbital environment matches with space debris and not spacecrafts . Thus it’s going to be benign.

…to be less benign.

Correct me if I am wrong.