Final answer:
The product of two rational numbers can always be written as a fraction. When multiplied, their numerators and denominators create a new fraction, or at its simplest form, a whole number represented as a fraction (e.g., 2/1). The correct answer is D. a fraction.
Step-by-step explanation:
The question is asking about the product of two rational numbers and what type of number this product will always result in. To clarify, a rational number is any number that can be expressed as a fraction, where the numerator (a) and the denominator (b) are both integers, and the denominator is not zero. A fraction is in the form of a/b, and it signifies a part of a whole. Ratios, like those describing proportions in chemistry, can also be represented as fractions or percentages. Scientific notation is a way of writing very large or very small numbers, and is not limited to integers but includes fractions as well.
When two rational numbers are multiplied, the product will always be a rational number. This is because the multiplication of two fractions involves multiplying their numerators to get the new numerator, and multiplying their denominators to get the new denominator. For example, if we multiply 1/2 by 3/4, we get (1*3)/(2*4), which simplifies to 3/8, still a fraction. Even if a fraction simplifies to a whole number, it can be written as a fraction (for example, 2 can be written as 2/1). Therefore, multiplying two rational numbers cannot result in an irrational number, as irrational numbers cannot be expressed as fractions with integer numerators and denominators.
Considering this, the correct option is D. a fraction.