Answer:
B.) Admittedly, we cannot reuse or recycle all of the materials we use in our daily lives.
and
D.) My opponent would use these limitations of our ability to recycle to counter my points about the materials we can recycle.
Both these sentences are countering the speaker's claim.
The answer would be B. Answers A, C, and D are fragments of a sentence, lacking a complete idea.
Ex:
A) "because I had not slept for hours" - "because" what? An example of a complete version of this sentence would be "My head hurts because I had not slept for hours."
the answer is she dips a corner of her sleeve/like a brush into water