题目内容：
Caroline has recently developed a new product. The nature of Caroline’s work is repetitive, and it is usual for there to be an 80% learning effect when a new product is developed. The time taken for the first unit was 22 minutes. An 80% learning effect applies.
What is the time to be taken for the fourth unit in minutes?
A 17.6 minutes
B 14.08 minutes
C 15.45 minutes
D 9.98 minutes
答案解析：