Answer :
The correct answer is B. Disruptive.
I disruptive natural selection the extreme values for a phenotype are favored. This causes a disruption in the middle of the graph for phenotype distribution, as there is a selection against the average phenotype, hence the name.
In this case of worms, the longest and the shortest worms are the most present, therefore we can conclude that the natural selection is disruptive and favors both of the extremes (short and long) of the phenotype.