A population of pigs lives on an island together with burrowing termites. Pigs that have the longest snouts tend to survive more frequently than those with shorter snouts. Over time, most of the pig population is made up of individuals that have very long snouts. This is an example of which type of selection?
directional selection
disruptive selection
stabilizing selection
ecosystem selection

a. directional selection

Explanation:

Directional selection refers to the type of natural selection that favors one extreme of the phenotypic or trait distribution while selects against the other extreme.This leads to the survival of one extreme while eradication of the other.The example of the giraffe's neck is a prominent example. As herbs and shrubs became scarce, the giraffes had to reach to the tree tops. Selection pressure favored the giraffes with the long necks whereas, those with shorter necks died out.