On a section of the planet with a limit of 4 units have a Marine

Zerg enemy executes an mobilize order on the  Marine planet

The Zerg faction has 6 units

How many units can attack the Zerg?

A) 1 marine VS 3 zerg (one units + 2)

B) 1 marine  VS 6 zerg ( 4 units limit + 2)

hi there

the maximum number of units you can attak with always depends on the unit limit of the section/area you attak and not on the unit number defending the area. so in this case you can attak the marine with 6 zerg units.

The popcap (unit limit) is checked for each player.

If the cap is 4, as in your example, the defender can have 4 stationed, and the attacker can mobilize 6(7) into the area. 

As skirmishes has to be maximized this usually means 4 skirmishes, unless the defender has Assist unit in which case they become support units the the number of skirmishes lowered to fit.

As all units must participate this means the attacker creates as many skirmishes as possible the then fill up with supporting units in the back lines (as he sees fit, all in one or spread out) until all units are engaged.

/Y