D) I am so terribly sorry., would be the most formal.
Answer:
A. He acts like he's going to cry.
Explanation:
A subordinating conjunction is a conjunction which marks a transition of time, place, cause or effect relationship between two ideas in the sentence. Also, it decreases the importance of one clause to make the reader analyze which idea among the two is more important than the other. Some of the examples of subordinating conjunction used in the given sentences are 'as', 'unless' and 'because'. In sentence A, there is no subordinating conjunction used.
