Remember that the primary method that the GRE, and honestly all standardized tests, use to generate difficulty is not introducing obscure concepts, but by presenting more information to process in a short period of time. So, when presented with a problem such as this, don't overreact, simply begin working through the problem methodically to arrive at the correct solution.

Since, each packer works 8 hours a day, we first need to determine the number of items produced by each packer:

A) 20 minutes per item, so 3 items per hour. 3 items x 8 hours = 24 items.
B) 24 minutes per item, so 2.5 items per hour. 2.5 items x 8 hours = 20 items.
C) 30 minutes per item, so 2 items per hour. 2 items x 8 hours = 16 items
D) 40 minutes per item, so 1.5 items per hour. 1.5 items x 8 hours = 12 items
E) 48 minutes per item, so 1.25 items per hour. 1.25 items x 8 hours = 10 items.

Now, determine the profit per worker based on their rates:

A) $100 - $66 = $34 profit per item. 34 x 24 = $816 profit.
B) $100 - $52 = $48 profit per item. 48 x 20 = $960 profit.
C) $100 - $46 = $54 profit per item. 54 x 16 = $864 profit.
D) $100 - $32 = $68 profit per item. 68 x 12 = $816 profit.
E) $100 - $28 = $72 profit per item. 72 x 10 = $720 profit.

Do note that Choices A and D are halving and doubling the relevant factors, so they may represent an opportunity for logical estimation that could allow you to not test those two options. Regardless, the correct answer is Choice B.