Final answer:
The first factor in an expression in scientific notation is called the coefficient, and it should be greater than or equal to 1 and less than 10.
Step-by-step explanation:
The first factor in an expression in scientific notation, represented by x, is called the coefficient.
In scientific notation, the coefficient should be greater than or equal to 1 and less than 10.
Therefore, the correct statement that describes this factor is A. 0≤x≤1.