Electrician input needed, don’t laugh

Well the one thing dad never taught me was electrical stuff.

I have a Kicker LED marine speaker to put in. The LED connector has red, green, blue, and black wires. I cut the connector off and stripped the wires.

Now I have to put a different connector on. This connector has red, green, black, and yellow wires.

Red to red. Green to green. Fine.

For the rest, Blue to black, or blue to yellow?

Ok I got the answer as I suspected. Yellow to blue, black to black. But had to be sure!