The commutator of a universal motor connects each armature coil to
a. the rotor.
c. the gearbox.
b. the shaft.
d. a brush.

a. the rotor

Explanation:

A commutator is a rotary electric switch that periodically changes the direction of the current between the rotor and the external circuit. In a motor provides energy to the rotor. It consists of a cylinder composed of multiple metal contact segments on the rotor.

in this image, you can see solar radiation going through ocean water.

no image, but probably absorption

conduction, convection, radiation