Which principal part is this verb form?

(have) ridden

A.

present

B.

past

C.

present participle

D.

past participle

This is not a present form, in the present the verb would be "rides" or "is ridding" and the present participle is "ridding",

it's also not simple past, which would be "rode"

the correct answer is the last one, D: it is the past participle. It's an irregular past participle: a regular one ends with - ed