Heat will only flow from one object to another a. if the object receiving the heat is larger b. if the object receiving the heat is denser c. if the object receiving the heat has a higher heat capacity d. if the object receiving the heat is at a lower temperature

There is a probability that heat will flow from higher to lower temperature,
and there is a probability that it will flow from lower to higher temperature. 

The probability that heat will flows from lower to higher temperature is so
small that it is taken to be a law of nature that heat will only flow to the
object that's at a lower temperature.