Hey.

Laser gyros have moving parts, it is correct. Please check this: http://en.wikipedia.org/wiki/Inertial_navigation_system#Laser_gyros
Lasers gyros have piezo-electric dither motor.

harbhla is right.laser ring gyros ae not in fact gyros,but sensorsof angular rate of rotationabout a single axis.they are made of a triangular block of temperature stable glass.very small tunnels are precisely drilled parallel to the perimeter of the triangle , and reflecting mirrors are placed in each corner.a small charge of Helium-neon gas is inserted and sealed into an aperture in the glass at the base of the triangle.......thus,laser gyros have no moving parts,A is the right answer..

i think a is the correct.Also wikepidia is not a textbook so i wouldnt recommend it.

My bad my academy's textbook clearly states that "a laser gyro has no moving parts " . So whoever sees this know it. This answer in this question is wrong. The a option is the correct.