What are the requirements for a sample to be considered representative?

A sample is considered representative when it accurately reflects the characteristics of the population from which it is drawn. For a sample to serve that purpose, it should be random, ensuring that every member of the population has an equal chance of being included. This randomness helps to reduce bias, allowing the results to be more generalizable.

Additionally, the sample size must be sufficiently large to capture the diversity and variability within the population. A larger sample size tends to provide more reliable estimates of population parameters and helps to minimize the effects of outliers or random variation. Therefore, a sample that is both random and large enough allows for a more accurate representation of the whole population's characteristics, making this choice the most appropriate.

The other options either focus on a non-random selection process or do not ensure a sample size sufficient to reflect the population accurately, leading to potential biases that could skew the results.