Answer:
To accelerate an object what has to increase the force.
Step-by-step explanation:
The rate of change of velocity is termed as the acceleration of the object. It is given as :

where
v is the final velocity
u is the initial velocity
According to Newton's seconds law of motion :
F = m a
where,
m is the mass of an object
a is the acceleration.
So, to accelerate an object the force acting on the it has to increase.
Hence, the correct option is (c) " the force ".