Why the correct answer is may?

[Rimma]

English Language Tests, Intermediate level

ESL/EFL Test #73 "Modal Medley", question 6

......... I have your permission to leave the meeting early?

(a) Will
(b) Would
(c) May

English Language Tests, Intermediate level

ESL/EFL Test #73 "Modal Medley", answer 6

May I have your permission to leave the meeting early?

Correct answer: (c) May
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Why the correct answer is may?
I don´t understand

Rimma

[Mister Micawber]

Only 'may' among these choices is correct as a modal for this request.
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Native English teacher at Mister Micawber's