The rule says an employer answers for injury an employee suffers while carrying out work in the course of that employment. The facts show X asking Y, a caterer's employee, to fetch a mechanic in exchange for payment, and Y getting hurt on that errand. Let's check each option.
X specifically engaged Y for the errand and agreed to pay him, so the accident happened while Y was working in the course of the employment X offered.
Therefore, the correct answer is X is liable as Y was working in the course of employment offered by X.
Courts often decide who counts as an "employer" for a given task by asking who had the right to control how, when and by whom the task was done, not by looking only at someone's regular payroll. Applying this control test here, X is the one who told Y exactly what to do, fetch the mechanic, and offered to pay him 1000 rupees for doing it, which puts X in control of that specific task regardless of who normally pays Y's wages.
Because X controlled the specific task Y was performing when he was hurt, and promised to pay him for it, X is the one answerable under the principle.
Therefore, the correct answer is X is liable as Y was working in the course of employment offered by X.