For this case we can translate the sentence given as:
What___________ in the market yesterday?
The sentence must be completed with the proper conjugation of the verb "buy" ("comprar" is Spanish)
From the simple perfect preterite we have:
Yo compré
Tú compraste
él/ella/Ud. compró
nosotros compramos
vosotros compramos
ellos/ellas/Uds. compraron
The sentence is in the second person singular, so the correct option is "compraste"
Answer:
Qué compraste en el mercado ayer?
A word that replaces the original subject in a sentence. Subject pronouns can be singular or plural, and they can be masculine, feminine, or gender neutral. The masculine or feminine subject pronoun is used when gender is known; when referring to an inanimate object, the gender-neutral form “it” is used. The subject pronoun “it” can be used to refer to animals of unspecific gender, and it is also appropriate to use the subject pronoun “it” to describe a baby of unknown gender. “It” is also used to talk about the weather, temperature, or time.
