Instructions: 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 an office, 50 percent of the workers have at least 5 years of service, and a total of 16 workers have at least 10 years of service. if 90 percent of the workers have fewer than 10 years of service, how many of the workers have at least 5 but fewer than 10 years of service ?
Options: a. 8, b. 64, c. 50, d. 144, e. 160
Output:
a