Consider the following relational algebra query: $$\Pi_{\mathtt{empId}} (\mathtt{employee}) - \Pi_{\mathtt{empId}} (\mathtt{employee} \bowtie_{(\mathtt{empId} = \mathtt{eId}) \wedge (\mathtt{empAge} \le \mathtt{depAge})} \mathtt{dependent})$$ The above query evaluates to the set of empIds of employees whose age is greater than that of

Let us analyze the query step-by-step:

1. The right-hand side subexpression:

selects the empId of all employees who have at least one dependent whose age is greater than or equal to the employee's age (i.e., $\text{empAge} \le \text{depAge}$).

2. The outer operation is a set difference:

This removes all employees who have at least one dependent with $\text{empAge} \le \text{depAge}$ from the set of all employees.

3. Since every employee is given to have at least one dependent, the remaining employees are those for whom no dependent satisfies $\text{empAge} \le \text{depAge}$, which means that for all of his/her dependents, $\text{empAge} > \text{depAge}$.

Therefore, the query returns the set of employees whose age is greater than that of all of his/her dependents (Option D).