请教一道数学

Q2:
On Saturday morning, Malachi will begin a camping vacation and he will return home at
the end of the first day on which it rains. If on the first three days of the vacation the
probability of rain on each day is 0.2, what is the probability that Malachi will return
home at the end of the day on the following Monday?
A. 0.008
B. 0.128
C. 0.488
D. 0.512
E. 0.640
Answer: is B.

思路是什么？谢谢！

Saturday和Sunday不能回来，这两天都不下雨，概率是0.8*0.8

Monday下雨0.2

so，0.8*0.8*0.2

谢谢指教！