What I say and what I do are not necessarily the same? Why?

[Carlos]

Test No. incompl/inter-9 "Say/Tell", question 6

What I ......... and what I do are not necessarily the same.

(a) said
(b) saying
(c) say
(d) tell

Test No. incompl/inter-9 "Say/Tell", answer 6

What I say and what I do are not necessarily the same.

Correct answer: (c) say

Your answer was: incorrect
What I said and what I do are not necessarily the same.
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Dera friends.
I think that "what I say and what I do"... is grammatically correct and follow the rule of the same verb form joined by and.
Please tell me what am I thinking wrong. Thanks a lot.

[Alan]

Yes, that's right and that's the answer!
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English as a Second Language
You can read my ESL story Three Letters for You?