Correct Option: D

The formula for kinetic energy in terms of momentum for fundamental particles is basically just a quantized version of the classical formula,

KE =	p2
	2m

, where KE is kinetic energy, p is momentum and m is the particle’s mass. In our case, Kinetic energy is constant, therefore p2 = 2m meaning that momentum is directly propor-tional to mass. The mass of particles in ascending order is: alpha, proton and electron. So Alpha particle will have the maximum momentum.