'who is speaking at this moment' vs 'who speaks at this moment'

[Umbro]

English Grammar Error, Intermediate level

ESL/EFL Test #8 "Tenses", question 8

Do you know the name of the person who speaks at this moment because I don't remember his name.

(a) Do
(b) speaks
(c) because
(d) remember

English Grammar Error, Intermediate level

ESL/EFL Test #8 "Tenses", answer 8

Do you know the name of the person who is speaking at this moment because I don't remember his name.

Correct entry: is speaking
The error was: (b) speaks
_________________________

Why not "speaks"?

Umbro

[Mister Micawber]

.
No, 'is speaking' at the moment.
.
_________________
Native English teacher at Mister Micawber's

[Bt_Unlock18]

how about 'the person who have spoken'?

[Mister Micawber]

No. 'person who has'.
_________________
Native English teacher at Mister Micawber's