निम्नलिखित में से कौन-सा गैर-संभाव्यता प्रतिदर्श (non-probability sampling) का एक व्यापक रूप से उपयोग किया जाने वाला वर्ग है जहां शोधकर्ता अध्ययन की विशिष्ट विशेषताओं और लक्ष्यों के आधार पर जानबूझकर नमूनों का चयन करता है?

Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R). Assertion (A): Though ex-post facto research examines cause and effect relationships, it is not part of experimental research. Reason (R): In ex-post facto research, the effect or change in the independent variable has already occurred and cannot be manipulated. In the light of the above statements, choose the most appropriate answer from the options given below:

Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R). Assertion (A): In non-probability sampling, the units are selected at the discretion of the researcher. Reason (R): Non-probability samples do not require a sampling frame. In the light of the above statements, choose the most appropriate answer from the options given below: