Why is random sampling preferred over other methods of sampling?

1) If you select a random sample, you can determine how many people you want in the sample.

2) A random sample is a fair way to select a sample, because each person in the population has an equal chance of getting selected.

3) A random sample is always the easiest way to select a sample from a population.

4) If you use a random sample, the sample mean will always be the same as the population mean.