Explanation:

- Lack of double coincidence of wants: Both parties must have what the other wants, making trades hard to arrange.

- Difficulty in the measurement of value: Without a common measure, comparing value gets complicated.

- Difficulty in store of value: Goods can perish or lose value, unlike money which can store value more effectively.

- People in the barter system face challenges in trading, valuing, and storing wealth due to these issues.

Option 4: All of these -- This is the correct answer as all these challenges collectively define the defects of the barter system.