The correct option is B trying - present participle
A gerund is a verb form which acts as a noun.A present participle form is the form of a verb, ending in-ing in English, which is used in forming continuous tenses. Option B)trying- present participle is correct as the word ends in -ing. The other options are wrong as no other tense can be used and to + verb is an infinitive. The correct answer is B)trying- present participle.