Answer:
B. The square root of 16 is 4., and 4 is a whole number. A whole number is a part of the rational family.
Explanation:
Remember: A rational number is any number that can be written into a fraction. Such as integers.
A is incorrect because 15 is not a whole numer, and it's decimals are not repeating with a pattern or terminating.
B is correct because the square root of 16, which is 4, is a whole number.
C is incorrect because 21 is not a whole numer, and it's decimals are not repeating with a pattern or terminating.
D is incorrect because 22 is not a whole numer, and it's decimals are not repeating with a pattern or terminating.