D. parallel structure just means that all of your verbs in the comma series line up in regards to tenses, here. in choice D, it's "BE friendly," "INTRODUCE yourself," and "SMILE." these are all present tense verbs.
the rest of the choices don't match--"exercise" and "stretching" are two different verb forms in choice A, "to go to the library" is the odd one out in choice B, ane "to build" doesn't match with the "-ing" verbs in choice C.
Answer:
i think they both attach different surfaces together
they both stick
I was just learning about this i believe the answer is A but in not positive<span />
Vonnegut was considered a success as a writer in 1960s.
The correct option is B.
You can test if there are two independent clauses by separating the clauses and seeing if they can stand alone.
They hadn't planned the trip. They returned to the store the next day and bought more peanut brittle.
Since the the two clauses can stand alone, there are two independent clauses.
Two independent clauses constitute a compound sentence.