Answer: ¿Cuánto pesan?
Step-by-step explanation: Ok, we have the response:
"Las manzanas pesan 1 libra. " which can be translated to:
"The apples weigh 1 pound."
And we must select the correct question, where the options are:
1) ¿Cuánto pesan? (How much do they weigh?)
2) ¿Cuánto cuestan? (How much they cost?)
3)¿Cuál es la fruta? (What is the fruit?)
4) ¿Cuál es la balanza? (what is the balance?)
Obviously, the correct option is the first one, ¿Cuánto pesan?