Answer :
Final answer:
A class III prescription balance and a counterbalance are both types of mechanical balance, more specifically a option(c).beam balance. They involve comparing unknown and known masses. Nowadays, they're commonly replaced by digital scales for more precision.
Explanation:
A class III prescription balance is a type of mechanical balance, specifically, a beam balance. This type of balance, often a double-pan balance, compares different masses by placing an object with an unknown mass in one pan and objects of known mass in the other pan. A similar principle applies to a counterbalance, which also uses a beam or lever system to achieve balance.
Within the materials you provided, it's mentioned that many mechanical balances, such as these, have been replaced by digital scales. Digital scales can measure the mass of an object more accurately and precisely, often up to the nearest thousandth of a gram, while a mechanical beam balance may only provide measurements to the nearest tenth of a gram.
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