Protons Are Being Accelerated in a Particle Accelerator $\sqrt { 2 }$

Multiple Choice

Protons are being accelerated in a particle accelerator.When the speed of the protons is doubled,their de Broglie wavelength will

A) increase by a factor of 4.
B) increase by a factor of 2.
C) decrease by a factor of 2.
D) increase by a factor of $\sqrt { 2 }$
E) decrease by a factor of $\sqrt { 2 }$