8th Ed. multiple combats CR

ok guys, there's a thing i just don't understand:

-my units A and B charge the enemy unit C
-C makes 5 wounds on A and 3 on B
-A makes 4 wounds, B makes 7 wounds

Now, determining CR what have I to do?

1) A loses by 1 point and tests at -1, C loses by 4 points against B and tests at -4?
2) C loses against 4+7 with 5+3 and tests at -3?
3) other?

 

Alternative 2. And c flees from the unit with most ranks, it doesn't matter which unit caused the most wounds.

 

thx, finally i know it!

 

Alternative 2 indeed but add this:
+1 to charge
So C would test at -4


extra tidbits:
+1 for a flank (if you had one) or even +2 for rear.
and both sides can add a SB once and a BSB, but you didn't mention those in your example