C It is a square root of a non-perfect square
A rational number is one that can be expressed as the ratio of two integers. The given decimal is a repeating decimal, which means it can be expressed as a fraction.
To show that it is a square root of a non-perfect square, we first need to realize that the decimal 0.747447444744447444447... can be written as 7/10 + 4/100 + 74/1000 + 744/10000 + 7(4444...)/10000000... = 7/10 + 4/100 + 74/1000 + 744/10000 + 7/(10^n) * (4444...)/(10000...), where n represents the number of 4's after the decimal point.
Now, let's simplify this expression as a fraction. We can rewrite it as (7/10 + 4/100 + 74/1000 + 744/10000)/(1 - 1/10^n).
The numerator is a finite sum of fractions, which is a rational number. The denominator, 1 - 1/10^n, is also a rational number because it is the difference of two rational numbers. Therefore, the entire expression is a rational number.
Hence, the given decimal is a rational number.