To solve this question, the user needs to have a basic understanding of grammar rules and verb tenses. The user must choose the correct verb form to complete the sentence.

Now, let's go through each option and explain why it is right or wrong:

A. Painted: This option is correct. To form the past tense of a regular verb, we add "-ed" to the base form of the verb. In this sentence, "had" is the helping verb, and "painted" is the past participle of the verb "paint". Thus, option A is the correct answer.

B. Paints: This option is incorrect because "paints" is the present tense form of the verb, and it does not match the past tense form needed in the sentence.

C. Painting: This option is incorrect because "painting" is the present participle form of the verb, and it does not match the past tense form needed in the sentence.

D. To paint: This option is incorrect because "to paint" is the infinitive form of the verb, and it does not match the past tense form needed in the sentence.

The Answer is: A