We cannot completely avoid stress in our lives. We need to find ways to cope with it. 

A Since we cannot completely avoid stress in our lives, we need to find ways to cope with it.

B Because stress can completely be avoided in our lives, we need to find ways to cope with it.

C After we can completely avoid stress in our lives, we need to find ways to cope with it.

D As long as we can completely avoid stress in our lives, we need to find ways to cope with it.