The correct option is C seen / eats
The given sentence takes two verbs. The first verb indicates an action that started in the past and has continued up till now. Thus, it will take the present perfect form of the verb. The second part mentions a habit or a general truth. Thus, it will take the simple present form of the verb.
"Saw/eats" in option A is incorrect as 'saw' uses the past participle form of the base verb 'see'.
"Seen/eat" in option B is incorrect. Both the verbs have taken the correct tense form. But, 'eat' is used with plural pronouns/nouns. The verb 'eats' is used with singular pronouns/nouns.
"Saw/eaten" in option C is incorrect as both verbs have taken the past participle form of their base verbs. This does not fit the context.
"Seen/eats" in option D is correct. "Seen" is the present perfect form of the verb 'see'. "Eats' is the correct present tense form of the verb is used with singular pronoun 'you'.
Thus, option D is correct.