Answer:
Third choice
π = 1/2 and 1 - π = 1/2
Explanation:
Formula for binomial distribution is

where
x is the number of successes
n = number of trials
π = probability of success on a single trial
The variance of the binomial distribution is

The maximum variance occurs when

Hence the correct choice is the third choice
π = 1/2 and 1- π = 1/2