Probability that none are male=(½)5=1/32. (The probability of female is also ½.)
Probability that just one is male is found by considering all the possible arrangements of puppies in the litter in which only one is male: MFFFF, FMFFF, FFMFF, FFFMF, FFFFM (5 positions of 1 male in the litter).
So the probability of just one male=5(½)5=5/32.
Add that to the probability of no males=6/32=3/16=0.1875 (answer option b).