The answer is B. Waddle.
A horse gallops, a duck waddles. Both are ways of moving. A horse gallops by moving its legs in a certain way, and a duck waddles by moving its legs in a different way.
A strut is a way of walking that is proud and confident. A prowl is a way of walking that is slow and stealthy. A trot is a way of walking that is faster than a walk but slower than a run.
Of
the four options, only waddle is a way of moving that is similar to gallop.