A worker wants to determine the average weight of fish fillets in his freezer. There are hundreds of boxes of fillets in the freezer with each box containing 15 fillets. He randomly selects 10 boxes...

A worker wants to determine the average weight of fish fillets in his freezer. There are hundreds of boxes of fillets in the freezer with each box containing 15 fillets. He randomly selects 10 boxes of fish at random and pools all fillets in the 10 chosen boxes together as his sample. Is this simple random sampling, stratified sampling, or cluster sampling?