You can tell a triple-beam balance is level when the a. three beams are all lined up b. balance tips back to the right c. object does not slide off the pan d. pointer lines up with the white line labeled 0

The correct answer is letter "C": object does not slide off the pan.

Explanation:

The Triple Beam Balance is a typical mechanical balance. It has a beam that is supported by a fulcrum. On one side is a pan on which the object is placed. On the other side, the beam is split into three parallel beams, each supporting one weight. In measuring the weight of an object, rather than adding additional weights, each of the three weights can be slid along the beam to increase their lever arm. Even if the three beams do not line up, as long as the object weighted is static, we can proceed to read the measure of the object.

i am sure the answer is d