It Could Be D. But If Not Then I would Go With A. Compare and Contrast
Answers are A. weak B. weak C. Strong D. weak E. weak. F. strong
I believe the answer is D (However) because C (Therefore) would not make sense as it means ‘for that reason’ or ‘consequently’, B (Then) is a time connective so that would not make sense as a transition word to connect the paragraph, and A (now) could be referred to as informal depending on how you use it, and it is commonly used as an adverb of time.
I hope this helped
The simple subject is obviously kittens.....