Answer:
The answer would be B and C
Explanation:
When you exercise your muscles start to contract as you work out tearing your muscles apart and rebuilding them to make you stronger. Also as you work out increase in blood co2 is a normal thing that always happens.
Trust me people I took health and PE class in 9th grade and our teacher asked us this same question and I gave him these answers and was correct.
so SHOOTZS!!!!!
