1. Le balcon: this is a masculine noun (le), and singular form (there is no -s to indicate the plural form), so you need a pronoun which is masculine and singular. The correct answer is lequel.
2. Le magasin: the same thing as with le balcon, the correct answer is lequel.
3. Les allergies: this is a masculine noun, and plural form (-s indicates that it is plural, singular would be allergie), which means that you need a pronoun which is masculine and plural. The correct answer is lesquels.
