No consuma comidas y bebidas dulces ni ácidas porque ocasionarán caries que causarán *dolor* en sus dientes. I need to fix the doler verb.
Would it be no dola or dola?

i would say "están" :

this question is given using the conditional form. conditional tenses are is used when talking about hypothetical situations and probabilities. also, this is used when making polite requests. so comprarías is the conjugation of the verb comprar that matches the second person singular in the conditional. finally:

¿cuál comprarías tú?

answer is a: las

explanation:

the reason for this answer is becouse it's a plural frase which talks more then one thing