In this sentence, the subject was someone who wandered the countryside and depended on the charity of others. Only one of our choices describes someone dependent on charity.
A "clerk" works in an office or a retail store. A "smuggler" transports illegal goods. A "clairvoyant" sees the future. An "opportunist" takes advantage of situations in negative ways, usually taking advantage of others. A "mendicant," though, is a beggar who depends on others.
The correct answer is (D).