To find the answer to your problem, we need to evaluate all the radicals given in the choices.
A) √20 => 4.472... | The right answer
B) 4.5 => 4.5 | Definitely wrong because 4.5 is not an irrational number.
C) √27 => 5.196... | Not between 4 and 5.
D) √9 => 3 | Not an irrational number
The answer to your query is A) √20. Hope this helps and have a wonderful day!
