Answer: The Great Depression was a hard time in US history because lots of people didn’t have enough money.
Explanation: The Great Depression was bad because people were really poor and didn’t work. The Great Depression was a difficult economic period because many didn’t have jobs.
The teachers present at the teacher's lounge could be there for a variety of reasons, for example it could even me a meeting of the supporters of the school uniform! his sample is therefore possibly biased - there is no way of knowing that it represents the whole population. He chose it because it was convenient to him - and the answer is "a, convenience sampling"