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: the distance from city a to city b is 120 miles. while driving from city a to city b, cara drives at a constant speed of 30 miles per hour. dan leaves city a 120 minutes after cara. what is the minimum constant speed in miles per hour that dan must exceed in order to arrive in city b before cara ?
Options: a. 42, b. 44, c. 60, d. 48, e. 50
c