Final answer:
A student should generally take 15-18 units each semester to graduate in four years.
Step-by-step explanation:
To graduate in four years, a student should generally take 15-18 units each semester. This allows for a total of 120 units over four years, which is the typical requirement for a bachelor's degree. Taking 15-18 units per semester ensures that the student fulfills the necessary course requirements and completes the degree within the expected timeframe.