The correct answer is option C - sixty-five.
When writing a compound number, that is a number made up of two words, we use a hyphen between each word. This occurs in numbers between twenty-one and ninety-nine. On the other hand, numbers higher than ninety-nine don't require a hyphen.
Besides, take into account that if the compound number is preceded by other numbers that don't require a hyphen, the rule is applied too, for example, four thousand and seventy-six.
