Some Marathons Allow Two Runners to "Split" the Marathon by Each

Some marathons allow two runners to "split" the marathon by each running a half marathon. Alice
And Sharon plan to split a marathon. Alice's half-marathon times average 92 minutes with a
Standard deviation of 4 minutes, and Sharon's half-marathon times average 96 minutes with a standard deviation of 2 minutes. Assume that the women's half-marathon times are independent.
The expected time for Alice and Sharon to complete a full marathon is 92 + 96 = 188 minutes. What
Is the standard deviation of
Their total time?

A) 2 minutes
B) 20 minutes
C) 6 minutes
D) It cannot be determined.
E) 4.5 minutes