Para mi cumpleaños, mamá siempre me mi comida favorita, arroz con pollo. a.)sirvo b.)servir c.)sirve d.)sirves

The correct answer is:  [C]:  "sirve" .

Note:  The subject is "mamá" ; which takes the "third person, singular"
subject pronoun.  Note that:  "sirve" ; is the "simple present tense" conjugation for the Spanish verb, "servir" — meaning "to serve" for this particular subject pronoun—which takes the "irregular form" (for this tense and for this particular subject pronoun.


→   " Para mi cumpleaños, mamá siempre me  sirve  mi comida favorita, arroz con pollo. "

→  which translates to:

 →  "For my birthday, mom always serves me my favorite meal [or, 'food'],  rice with chicken" .

Consider the other answer choices:

Choice:  [A]:  "sirvo" ; is incorrect.  This is the conjugation for the first person, singular, simple present tense, of the Spanish verb, "servir" —
meaning "to serve"— which takes an irregular form for this particular verb tense associated for this particular subject pronoun, "yo" (Spanish word/pronoun for "I" ; and this conjugation means: "I serve" — "[Yo] sirvo" ; which does not correspond with the subject provided—"mamá" ; and as such, is INCORRECT.

Choice:  [B]:  "servir" ; is incorrect.  This Spanish verb means: "to serve". 

This Spanish verb is provided in the "infinitive form" ; so it is INCORRECT; since the Spanish verb:  "servir" ; is not conjugated; and does not correspond with the subject provided—"mamá" .

Choice:  [D]:  "sirves" ; is incorrect.  This is the conjugation for the second person, singular, simple present tense, of the Spanish verb, "servir" — 
meaning "to serve"— which takes an irregular form for this particular verb tense associated for this particular subject pronoun, "tú" (Spanish word/pronoun for "you";  singular, informal format;  meaning: "You serve" — "[Tú] sirves" ; refers to what "you" do— in this case:  "you serve" / when referring to one person; and in the familiar/informal sense; e.g. a close friend or child; and this answer choice—"sirves" —  does not correspond with the subject provided—"mamá" ; and as such, is INCORRECT.