4. D
5. C
6.C
Hope this helps :)
Answer:
Smoking, drinking and taking substances can cause an early pregnancy
Explanation:
A) remain in the body after production
B) flag antigens for destruction
C) are an important part of the immune system
D) all of the above
D) ALL ARE CORRECT!!
Answer:
The process uses fuel that is expensive.
Explanation:
hope this helps