Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Problem: a cube of edge 16 cm is immersed completely in a rectangular vessel containing water. if the dimensions of the base of vessel are 20 cm * 15 cm, find the rise in water level ?
Options: a. 6 cm, b. 8.25 cm, c. 13.65 cm, d. 15.12 cm, e. 20.62 cm
c