The property of matter that determines the direction of heat flow is the

Temperature

Explanation:

The heat flows from high temperature to low temperature.So we can say that temperature is the property that decide the direction of heat flow.Like in the electric system current flow high voltage to low voltage ,so we can say that voltage is the property which determine the direction of current flow.

So the answer is Temperature.

it is called kinetic energy

the answer is b, have negligible mass