A major consumer products company wants to measure the quality of the packaging of their products on the store shelves. In a chain grocery store, all of the packages of a 15-ounce Wild Berry shampoo and all of the packages of a 4-ounce Man-O-Manly deodorant are sampled. What sampling method is being used for this sampling plan?(Points : 1)

cluster sampling

simple random sampling

continuous sampling

protracted random sampling