B

Step 1: The particle is moving in a horizontal circle with uniform speed, meaning the speed remains constant throughout the motion.
Step 2: The kinetic energy (KE) of the particle is given by the formula:
$$ KE = \frac{1}{2} MV^2 $$
Since both mass (M) and speed (V) remain constant, the kinetic energy does not change as the particle moves around the circle.
Therefore, the change in kinetic energy is zero.
Step 3: Momentum is defined as the product of mass and velocity. While the direction of velocity changes, the magnitude of velocity does not, hence the magnitude of momentum remains the same throughout the motion.
Therefore, momentum does not change.
Hence, the correct answer is B.