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.

[EX Q]: Problem: what will be the compound interest on a sum of rs. 20,000 after 3 years at the rate of 12 % p. a. ?
Options: a. rs. 8098.56, b. rs. 9720, c. rs. 10123.20, d. rs. 10483.20, e. none
[EX A]: a

[EX Q]: Problem: what will be the percentage increase in the area of the cube ' s surface if each of the cube ' s edges grows by 40 % ?
Options: a. 95 %, b. 90 %, c. 85 %, d. 96 %, e. 25 %
[EX A]: d

[EX Q]: Problem: every letter in the alphabet has a number value that is equal to its place in the alphabet. thus, the letter a has a value of 1, the letter b has a value of 2, the letter c has a value of 3, etc... the number value of a word is obtained by adding up the value of the letters in the word and then multiplying that sum by the length of the word. what is the number value of the word ` ` hen ' ' ?
Options: a. 69, b. 72, c. 75, d. 78, e. 81
[EX A]:
e