Which condition causes the palindrome-checking function to return false?

• A. The characters at mirrored positions are equal.
• B. The characters at mirrored positions are different.
• C. The string is empty.
• D. The string contains only one character.

Answer: (B)

Checking whether a string reads the same forwards and backwards is the idea. A palindrome check compares characters from opposite ends moving toward the center. If all mirrored pairs match, the string is a palindrome and the function returns true. If any mirrored pair differs, the string cannot be read the same both ways, so the function returns false. This is why the condition that makes it return false is when the characters at mirrored positions are different. For example, 'racecar' is a palindrome because each mirrored pair matches. An example with a mismatch like 'abca' has 'b' and 'c' as the next pair after the ends, which differ, so it's not a palindrome and would yield false. The empty string or a string with a single character are palindromes, since there are no mismatched mirrored pairs, so they would return true.