"M na-akụ egwu." - Kedu okwu na-eme atụmatụ oge?

The sentence M na-aku egwu means "I am playing music/drumming." The question asks which word indicates tense (atumatu oge) - that is, which word tells us WHEN the action is happening.

In Igbo grammar, tense is marked by auxiliary verb constructions. In this sentence, na-aku is the present continuous (progressive) tense form. The prefix na- is the Igbo present continuous tense marker. It attaches to the verb root aku (to play/drum) to show that the action is happening right now, at this moment. Together, na-aku functions as the tense-bearing element of the sentence.

The other words do not mark tense: M is the subject pronoun (I), egwu is the noun (music/drum), and akwu does not appear in this sentence as written. The word that carries the tense information is na-aku.