Final answer:
In this sentence, the appropriate word to fill in the blank is 'les,' which is the indirect object pronoun used to indicate 'to them' or 'to their'.
Step-by-step explanation:
The appropriate word to fill in the blank in this sentence is les. The sentence translates to 'Parents always ask their children for a lot of homework.'
In Spanish, 'les' is the indirect object pronoun used to indicate the third person plural form of 'to them' or 'to their.'
For example, 'Les pido ayuda a mis amigos' translates to 'I ask for help from my friends'.
Learn more about Indirect Object Pronouns in Spanish