In suspended type moving coil galvanometer, quartz suspension is used because

The correct option is: Elastic after effects are negligible.

Detailed Explanation:
In a suspended type moving coil galvanometer, a fine suspension fiber is used to suspend the coil between the magnetic pole pieces. When current passes through the coil, it experiences a deflecting magnetic torque and rotates, which twists the suspension fiber. The twisted fiber produces an elastic restoring torque to oppose this rotation.

The restoring torque is mathematically expressed as:
$\tau =C\theta$
where $C$ is the torsional constant of the suspension fiber and $\theta$ is the angle of twist.

When the current is switched off, the deflecting torque ceases, and the restoring torque is responsible for bringing the coil back to its original equilibrium (zero) position immediately.

However, most materials exhibit a phenomenon called elastic after-effect, which is the delay in returning to the original un-deformed state after the deforming force is removed. If the suspension fiber has a large elastic after-effect, the coil and pointer will take a significant amount of time to return to zero, causing lag and inaccuracies in subsequent measurements.

Quartz is highly preferred because its elastic after-effects are negligible. It returns to its original un-deformed state almost instantaneously when the deflecting torque is removed, ensuring quick and accurate measurements.