Which of the following motor ingredients improves the mortar's workability?

The ingredient that significantly enhances the workability of mortar is lime. Lime is often added to mortar mixes because it improves the plasticity and workability, making it easier for masons to apply and manipulate the mortar during construction. Its presence helps achieve a smoother, more workable paste that aids in bonding materials together effectively.

In contrast, water is primarily used to hydrate the cement and initiate the chemical processes involved in curing but does not alone enhance workability. While clay can sometimes assist in providing some plasticity, it is not a standard ingredient in most mortar mixes and can lead to inconsistencies in performance. Cement, while essential for strength in mortar, can create a stiffer mix that may reduce workability if not balanced properly with other ingredients. Therefore, lime is recognized as the best option for improving the workability of mortar in construction applications.