Can the SEP IRA contribution be based on individual Schedule C?

I have 3 Schedule C businesses. Business A was very profitable last year, but B and C were not. Can I calculate the SEP IRA contribution based only on Business A by making the income adjustment to offset Business B's and C's losses?

For example, A has $100k profit but B and C have $100K losses. I want to make SEP IRA contribution only based on Business A but Turbotax is calculating my net income as zero thus no contribution. Am I allowed to only use Business A's income for the SEP IRA contribution calculation?