Momentum is a vector quantity because it has both magnitude and direction, paralleling the direction of the velocity vector. Option A is correct.
Momentum is a quantity that not only has a magnitude but also a direction, which means it can point left, right, up, or down. Therefore, it is a vector quantity. Vectors are defined by both their magnitude and direction, and this is true for momentum as well.
For example, momentum is often divided into components along the x, y, and sometimes z axes when solving physics problems. The momentum of an object is the product of its mass, which is a scalar, and its velocity, which is a vector. The direction of the momentum vector is the same as the direction of the velocity.
Hence, A. is the correct option.