Answer:
The correct answer is - option D. a pen.
Explanation:
A triple beam balance is an instrument which is a type of lever used to measure the mass of an unknown mass object very precisely. This instrument shows a very small error of ±0.05 grams.
It has a measurement tray on one side of the instrument and a fulcrum on the other side. On the measurement tray, an object with an unknown mass is placed and a set of sliding weights on the fulcrum. The sliding weights called riders that slide on beams to balance the object. The maximum weight a triple beam balance can measure is 610 grams ( 10+500+100).
Thus, the correct answer among these options is - option D.a pen.