How can I Instantiate an object with a random y rotation but in 90 degree increments?

I am pretty much a complete noob at coding. I’ve setup a float with 0, 90, 180, and 270 but I can’t figure out how to instantiate my tiles with the random y set to one of the above angles. Any help would be greatly appreciated.

Instantiate( prefab, position, Quaternion.Euler( 0, angles[ Random.Range( 0, angles.Length ) ], 0 ) );

Without the array:

Instantiate( prefab, position, Quaternion.Euler( 0, Random.Range( 0, 4 ) * 90, 0 ) );