When you see someone you have a crush on and your heart pounds, your hands get sweaty, and your cheeks feel hot, your is/are active?

Salutations!

When you see someone you have a crush on and your heart pounds, your hands get sweaty, and your cheeks feel hot, your is/are active.

When you see someone you have a crush on and your heart pounds, your hands get sweaty, and your cheeks feel hot, your autonomic nervous system is/are active

Hope I helped!