Answer:
Option (B) is the correct answer.
Explanation:
Let 'x' the starting point be
She walks down 2 flights to visit a friend.
so walking down means we need to add 2 units to the starting point x

Then he walks up 3 flights to deliver a message to a neighbor.
now subtracting 3 units from (x+2)

x = -1 means now he is UP to 1 point where he started his flight.
Thus, he needs to walk down 1 more flight to reach her starting point
Thus, -1 is the number of flights Brandie must walk to get back to her starting point.
Therefore, option (B) is the correct answer.