Identify the type of sampling used (random, systematic, convenience, stratified, or cluster sampling) in the situation described below. In a poll conducted by a certain research center, 945 adults were called after their telephone numbers were randomly generated by a computer, and 37 % were able to correctly identify the president. Which type of sampling did the research center use? 1. Systematic sampling 2. Cluster sampling 3. Random sampling 4. Convenience sampling 5. Stratified sampling