Answer:

To answer this question, we need to understand what a kilogram (kg) is and how it is measured.

What is a kilogram?
A kilogram is a unit of measurement used to quantify mass. Mass refers to the amount of matter in an object, and it is commonly measured in kilograms.

Examples of objects that can be measured in kilograms:
Among the given options, the object that can be measured in kilograms is a sack of rice.

Why is a sack of rice the correct answer?
A sack of rice is a larger object that contains a significant amount of matter. It can be weighed using a weighing scale, and the result will be in kilograms. The weight of the rice will determine the measurement in kilograms.

Why are the other options incorrect?
- Pencil: A pencil is a small object that typically weighs only a few grams. It is not appropriate to measure its weight in kilograms.
- An orange: Like a pencil, an orange is also a small object that weighs only a few grams. It is not appropriate to measure its weight in kilograms.
- A ball: A ball can vary in size and weight, but most balls are not large enough to be measured in kilograms. They are usually measured in grams or ounces.

Conclusion:
In conclusion, a sack of rice is the correct answer because it is a larger object that can be measured in kilograms. The other options, such as a pencil, an orange, and a ball, are smaller objects that are typically measured in grams or ounces.