D. Marilyn’s husband, Bruce, is an entertaining fellow.
E. Monica ate Evan’s undercooked pasta down to the last bite.
A participle is a word formed from a verb that works as an adjective. There are two types of participles: the present participle (which ends in -ing) and the past participle (that are formed from the past tense of a verb, they usually has the ending -ed, -d, -t, -en, or -n).
In Sentence D. "entertaining" is the participle (the present one) as it describes a noun "fellow". And it is formed from the verb "entertain".
In Sentence E. "undercooked" is the participle (the past one) as it describes a noun "pasta". And it is formed from the verb "undercook".