The man's incredible generosity in gifting ten thousand dollars toward the scholarship drive was unexpected but welcomed

The root of the word is cred, which means "to believe." The prefix of the word is in, which means "not." Based on its root and prefix, which might incredible mean in this sentence?
(1 point)
• believable
• showing approval
• kindhearted
• impossible to believe

Based on its root and prefix, in this sentence, "incredible" might mean "impossible to believe."