Fibonacci numbers, commonly denoted Fn form a sequence called the Fibonacci sequence, in which each number is the sum of the two previous ones, starting from 0 and 1.
Eh … neither is 144 the only prime Fibonacci number (I can think of 2, 3, 5, 13 from the top of my head), nor is it a prime number at all. Perhaps the questioner intended to ask for the only Fibonacci number that is a perfect square? Still the answer 144 would be wrong, as 0 and 1 are both Fibonacci numbers (at least by the convention the “answer” uses) …
Eh … neither is 144 the only prime Fibonacci number (I can think of 2, 3, 5, 13 from the top of my head), nor is it a prime number at all. Perhaps the questioner intended to ask for the only Fibonacci number that is a perfect square? Still the answer 144 would be wrong, as 0 and 1 are both Fibonacci numbers (at least by the convention the “answer” uses) …