What is the product of -3 and -7?

To find the product of -3 and -7, you multiply the two numbers together. When you multiply two negative numbers, the result is always positive. This is based on the rules of multiplication in mathematics, where the product of two negative integers yields a positive integer.

In this case:

• Multiply 3 and 7, which gives you 21.
• Since both numbers being multiplied are negative, the product becomes positive.

Thus, the product of -3 and -7 is 21. This is why the correct answer is the positive number 21, as it adheres to the rule that states that multiplying two negatives results in a positive value.