A fool at 40 is a fool forever?

[Dinanrodrig]

English Language Tests, Intermediate level

ESL/EFL Test #296 "English Slang Idioms (18)", question 5

"Can you believe that he spent his kids' college fund again on another new car? Well, a fool at 40 is a fool .........," Gina gossiped to her friend Laura.

(a) forever
(b) at 50
(c) indeed
(d) tomorrow

English Language Tests, Intermediate level

ESL/EFL Test #296 "English Slang Idioms (18)", answer 5

"Can you believe that he spent his kids' college fund again on another new car? Well, a fool at 40 is a fool forever," Gina gossiped to her friend Laura.

Correct answer: (a) forever

Your answer was: incorrect
"Can you believe that he spent his kids' college fund again on another new car? Well, a fool at 40 is a fool indeed," Gina gossiped to her friend Laura.
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Isn't my choice possible?

[Our Tort System]

Maybe, but it's not the best answer. The best answer is "forever" because the saying reads "a fool at 40 is a fool forever".
You can find the definition here: http://www.usingenglish.com/reference/idioms/a+fool+at+40+is+a+fool+forever.html
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