An unbaised coin is thrown 5 times. Let X be a random variable and k be the value of assigned to X for k=3,4,5 times Head occurs consecutively and otherwise the value of X is assigned -1. What is value of expection.
A. `(1)/(8)`
B. `-(1)/(8)`
C. `(3)/(8)`
D. `-(3)/(8)`
