You misunderstood the question. It's not about which tool to use, it's about where to cut.
He's got a plan like this:

Now the question is whether the line is part of the board to cut or not. If it's part of the board, you would cut close to the line, leaving it intact. However, if you cut like this, cutting out board A would remove the thickness of your sawblade + the thickness of the line from board B.
So the answer to his question is to cut on the line, thereby removing equal parts from board A and board B.
However, this is probably moot because the OP didn't bother to log in for 6 days.