The correct answer is option 4: the sum of the n positive numbers is never less than n.

To understand why this is the correct answer, let`s consider the given statement that the product of n positive numbers is unity. In other words, the numbers multiply together to give a result of 1.

If we assume that at least one of the numbers is less than 1, then the product would also be less than 1. However, since the product is unity (1), it means that all the numbers must be equal to 1.

Now, let`s consider the sum of these n numbers. Since all the numbers are equal to 1, the sum of n numbers would be n * 1 = n.

Therefore, the sum of the n positive numbers is always equal to n. Since n is a positive integer (since it represents the number of positive numbers), we can conclude that the sum is never less than n.

Therefore, option 4 is the correct answer.