Velocity is the combination of which of the following?
a. force & direction
b. speed & direction
c. gravity & direction
d. speed & momentum

Before going to reach at our conclusion first we have to know the basic idea about velocity.

Velocity of a body is defined as the rate of change of displacement of a body between two points or locations. As we know that displacement is a vector quantity having magnitude and  specific direction ,so velocity is also considered as a vector quantity.

If a particle is moving along a straight  line path, the magnitude of the rate of change of displacement  or velocity will be numerically equal to the sped of the body which is a scalar quantity,.

Hence speed in a particular direction is called velocity.

The momentum is mass times  the velocity  i.e P= MV.

And gravity is the mutual force of attraction between any bodies of the universe which is mathematically represented as

                      where are the mass of two bodies and R is the separation distance between them.                

Hence option b is the right answer.