The correct option is: It increases the kinetic energy.
Kinetic energy (KE) is given by the formula:
\[ KE = \frac{1}{2} mv^2 \]
where \(m\) is the mass of the object and \(v\) is its speed. From this equation, you can see that if the mass \(m\) increases while the speed \(v\) remains constant, the kinetic energy will also increase. Therefore, increasing the mass of an object leads to an increase in its kinetic energy if the speed is constant.