Question

To meet the requirements for random sampling you must....

Answer 1

There are two requirements for random sampling

1.) Since because of random ( => No bias for any observation ) that is for each individual there is equal chance / probability for being selected. That is if we have 10 observations, then probability of each individual to be selected in first draw is (1/10)

2.) If more than one individual is to be selected in a sample ( that is sample size is more than 1 ), then there should be constant probability for each and every selection.