Which of the following is not a restricted random sampling technique?

Stratified Sampling:
Explanation: Stratified sampling is a restricted random sampling technique where the population is divided into subgroups or strata based on certain characteristics, and then samples are randomly selected from each stratum.

Simple Random Sampling:
Explanation: Simple random sampling is a pure random sampling technique where every individual in the population has an equal chance of being selected.

Systematic Sampling:
Explanation: Systematic sampling is a restricted random sampling technique where a random start point is chosen, and then every kth individual is selected.

Multi-stage Sampling:
Explanation: Multi-stage sampling involves a combination of various sampling techniques in multiple stages to create a more complex sampling design.

In the context of the question, Simple Random Sampling is not a restricted technique; it is the most basic and unrestricted form of random sampling where each individual has an equal chance of being selected.

Therefore, the correct answer is Option B: Simple random sampling.