The principle makes a master liable for whatever his servant does in the course of his duties. Y was employed by X specifically as the property in-charge, meaning receiving construction material and issuing receipts for it was part of his assigned job. Let's evaluate each option against this principle:
Since Y's acceptance of the cement and issuance of the receipt fell within the course of his duties, the principle of vicarious liability fixes the entire obligation on X.
Therefore, the correct answer is X is liable for the entire amount.
The principle of vicarious liability can also be tested through the three conditions it actually requires: first, that a master-servant relationship exists between X and Y; second, that the act in question falls within the course of duties Y was engaged to perform; and third, that the outside party dealing with Y did so in reliance on Y's authority to act for X. Applying these three conditions to each option shows which conclusion follows:
All three conditions of the principle point to the same outcome, X answers to Z for the material Y received and receipted as part of his job.
Therefore, the correct answer is X is liable for the entire amount.