Hello there! Your answer is B.
A rational number is just a number that can be expressed as a fraction.
Let's start by simplifying each number:
A. [tex]-\sqrt{16}[/tex] = -4 or -4/1
B. [tex]\sqrt{0.4}[/tex] = 0.63245553203...
C. [tex]\sqrt{4}[/tex] = 2 or 2/1
D. [tex]\sqrt{16}[/tex] = 4 or 4/1
Out of the options given, all of them can be simplified into a fraction, except for the second one, so that means that the second one is our irrational number.
