What form is the underlined verb in the sentence?

they have ridden that roller coaster three times already.

--ridden is the underlined word

a.
past participle

b.
past

c.
present participle

d.
present

In which situations would you need to compromise to avoid stress and conflict a) when forcing others to see things your way b) when delegating work c) when using the i-statement d) when dealing with changes in organization