-0.91 is not a rational number. ( option C)
Rational numbers are real numbers that can be expressed as a ratio of two integers, where the denominator is not zero. They include integers and fractions. Examples are -3, 1/2, and 7.
From the options given,
745 is an integer and whole number and and it's therefore a rational number.
16 is also an integer and rational number while 3/4 is a fraction and also a rational number.
The only number that is not a rational number is -0.91 because it can not be expressed a s a fraction.