The correct answer is: [A]: " -1 " .
_________________________
Note: Among the three (3) answer choices given: "-1" ; "0" , and "50" ;
The numbers: "0" and "50" are both considered "integers" and "whole numbers". Note that "negative numbers" (that do not contain any fractions or decimals) — such as " -1 " — are considered "integers" but NOT "whole numbers" .
→ As such, the remaining answer choice: " -1 " ;
→ which is: "Answer choice: [A]: " -1 " ; is the correct answer.
_________________________