A set of integers can be classified as positive, negative, or zero. Which of the following statements about multiplying positive and negative integers is ALWAYS true?

When multiplying a positive integer by a negative integer, the product will always be negative. This is a fundamental rule of arithmetic. The sign of the product is determined by the rule that states a positive number multiplied by a negative number results in a negative number. Therefore, the statement that the product will always be negative is always true when multiplying positive and negative integers. Choice A is incorrect because the product is not always positive when multiplying positive and negative integers. Choice C is incorrect because the product is not dependent on the specific numbers but on the signs of the integers being multiplied. Choice D is incorrect as positive and negative integers can be multiplied.