What Type of Sample Divides the Population into Nonoverlapping Groups

Multiple Choice

What type of sample divides the population into nonoverlapping groups of N₁,N₂,N₃,...Ni,such that N₁ + N₂ + N₃ + ...+ Ni + N = N,and then performs a simple random sample of ƒ = n/N in each of the nonoverlapping groups?​

A) simple random
B) stratified random
C) systematic random
D) cluster random