What creates the humorous effect in the passage?
a. the other sons of the speaker pretending to be sensible
b. maturity turning dull even at a tender age
c. dullness and stupidity being regarded as admirable traits
d. the choice of an heir based on close physical resemblance

mac flecknoe by john dryden (excerpt)

all humane things are subiect to decay, and when fate summons, monarch's must obey; this flecknoe found, who like augustus young, was call'd to empire, and had govern'd long; in prose and verse was own'd without dispute, through all the realms of nonsense, absolute; this aged prince now flourishing in peace, and blest with issue of a large increase, worn out with business, did at length debate, to settle the succession of the state, and pond'ring, which of all his sons were fit to reign, and wage immortal wars, with wit, cry'd 'tis resov'd (for nature pleads, that he should only rule, who most resembles me,) alone my perfect image bears, mature in dulness from his tender years; alone of all my sons, is he who stands confirm'd in full stupidity; the rest, to some faint meaning make pretence, but shad-- never deviates into sence;