A.an edge on a map because you won't have any boundary's on a ruler, scarf, or a street sign
Taking notes about a speaker's topic before hearing the speech
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.
Gravity is a natural phenomenon
or
Mirages are a common desert phenomenon
Each time a new social media app is revealed to the world it becomes a phenomenon for a while and then slowly fades into unimportance
