Define type 1 superconductor.

By reflecting _____ of known wavelength of different layers of the crystal the distance between the layers and hence the unit cell edge length can be determined. 

A : X-rays

B : UV-rays

C : Gamma-rays

Enter your correct answer as A, B or C.

Represent the union of two sets by Venn diagram for each of the following.

$X=\{x | x$ is a prime number between $80$ and $100\}$

$Y=\{y | y$ is an odd number between $90$ and $100\}$