The answer is the last one, D. All of the other transitions indicate that the writer will either go into further detail on the subject or list other reasons as to why this would be correct. However, D clearly uses a contrasting transition to introduce a new argument.
I believe it's the writing process.
Answer:
If you saw a really big spider, then what would you do?
*sorry about the misinterpretation*
Hope this helps :)
Should shouldn’t should shouldn’t should