An outlet pipe can empty 2/3 of a cistern in 16 minutes. In 4 minutes, what part of the cistern will be emptied?	Choose one
A) 1 / 2  B) 1 / 3  C) 1 / 4  D) 1 / 6  E) 1 / 8

Rationale: "4 / 16 * 2 / 3 = 1 / 6 the answer is d ."
Answer: D