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

Multiple Choice

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