Lesson 6: Maintaining a Healthy weight test

Question 4: Your skin, lings, and kidneys are all part of the _______. Which removes wastes from the body.
A: gallbladder
B: enzyme
C: excretory
D: nervous system
I thinks it's A, but I'm not sure and I really need help

I also need help with questions 5, 8 and 10 thank you