What is known as a collection of all the elements of interest?

The correct answer is population because, in statistics, a population encompasses the entire group or collection of all elements or individuals that share a common characteristic of interest. When statisticians refer to a population, they mean the totality of observations that are being studied, whether these are people, animals, or objects, depending on the context of the research.

In contrast, a sample refers to a subset of the population that is selected for analysis. A sample is generally used to estimate characteristics of the larger population without needing to assess every individual within that population, which can be impractical. The term subset is more general and refers to any portion or segment of a set, not necessarily tied to statistical populations or sampling. Lastly, an element is an individual member of a population or sample, rather than a collection. Thus, while each of these terms has a specific meaning in statistics, only "population" accurately describes the entirety of the elements in question.