Final answer:
The exponent ('b') in scientific notation must be an integer. So, the correct answer is D) Integer. This allows for the simple manipulation of large or small numbers using scientific notation.
Step-by-step explanation:
In scientific notation, a number is expressed as the product of two parts: a coefficient and the number 10 raised to a power. The coefficient must be a number between 1 and 10, and the exponent must be an integer. So, in the context of scientific notation, when we state that 'a' has to be between 1 and 10 while 'b' has to be an integer, it implies that the exponent part of scientific notation (which is 'b') can be a positive or negative whole number, including zero (10⁰ = 1).
Therefore, the answer to the student's question is D) Integer. Scientific notation uses a coefficient that is between 1 and not more than 10, and an exponent that is an integer. This efficient system simplifies the manipulation of very large or very small numbers, making it easier to work with them in fields such as physics and chemistry.