Final answer:
Option (a), The phrase that aligns with "weigh" is "Tip the scales at," meaning to register a weight on a scale. A balance or scale is used to measure weight, and kilograms would be the appropriate metric unit for heavier items like a box of books.
Step-by-step explanation:
The phrase that matches the word "weigh" among the given options is "Tip the scales at." This idiomatically means to register a weight by tipping the scales. None of the other options (Run a marathon, Bake a cake, Write a letter) are associated with measuring weight.
To measure something's weight, we often use a scale or a balance. For example, to measure the weight of a bag of sand or a bunch of bananas, a scale is appropriate. When dealing with heavier objects that exceed a scale's capacity, you might use a simple fulcrum with a spring scale to measure the object, as it can help determine the weight beyond the maximum reading on the scale.
If we are measuring metric units of weight, like in the case of Jesse in the mailroom, kilograms would be a suitable unit to weigh a box containing books and documents.