Suppose an Oil Tanker Hits a Reef and Begins to Leak

Multiple Choice

Suppose an oil tanker hits a reef and begins to leak. The efforts of the workers repairing the leak cause the rate at which the oil is leaking to decrease. The oil was leaking at a rate of 39 barrels per hour at the end of the first hour after the accident, and the rate is decreasing at a rate of one barrel per hour. How many barrels of oil will leak in the first 6 hours? ​

A) 216 barrels
B) 132 barrels
C) 222 barrels
D) 231 barrels
E) 225 barrels