Definition: 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.
Input: Problem: in 7 given numbers, the average of first 4 numbers is 4 and that of last 4 numbers is also 4. if the average of these 7 numbers is 3, the fourth number is ?
Options: a. 3, b. 4, c. 7, d. 11, e. 12
Output:
d