In grammar, inflection is the modification of a word to express different grammatical categories such as tense, case, voice, aspect, person, number, gender, and mood.
Now, we have this conjugation of the verb "to play": playing.
Let's see the possible answers:
A. infinitive: no, a verb in infinitive does not have any conjugation; thus, this option is no the correct one.
B. Present, third person singular: this conjugation applies to a specific moment and pronoun: present - usually or currently happens -, and pronoun, thind person singular: he/she/it. Example of the verb conjugated in that form: she plays, he plays, it plays.
C. Past tense: this is used to talk about actions that already took place. Conjugation of the verb "play" for all the pronouns in past tense: I played, you played, she played...
D. This is the correct answer: present participle. The present participle is the form of a verb used in forming continuous tenses; its structure - almost always - is the basic form of the verb, plus ING ending. Example: PLAY - ING. Playing.
Correct answer is D.
Hope this helps