The following items are available for use in a pan balance to measure the weight of a large rock. Which items will yield the greatest level of accuracy, that is, approximate the true weight of the rock with the least error? You may only use items of the kind selected, and may not mix items.

A. marbles

B. salt

C. basketballs

D. oranges

The correct option is B.

Pan balance is one of the instruments that are used to measure weights of objects. The instrument is designed in such a way that, it has two pans and a standard weight can be added to one of the pan to determine the weight of the object in the other pan. In the question given above, the pan balance is to be used to measure the weight of a large rock. Salt is the right object to be used on the second pan because it can be packaged in standard weights and it is very light in weight. So, it will be very sensitive to the weight of the rock that is been added on the other pan.