The correct answer is D because Workday provides cross plan insurance rules specifically to control relationships between elections across multiple insurance plans. When one plan's maximum coverage must be calculated as a percentage of another plan's election, the correct configuration is a cross plan insurance percentage maximum. In this case, the Spousal Life plan must be capped at 50% of the employee's Voluntary Supplemental Life election, so the system needs a rule that compares the two plans and enforces that percentage-based limit during enrollment.

Option A is incorrect because an eligibility rule determines whether a worker can enroll in a plan, not how one insurance election is mathematically limited by another. Option B is also incorrect because business process validations are not the standard configuration method for enforcing insurance coverage relationships during benefit elections. Option C does not solve the requirement either, since a prerequisite can require another election but does not impose a percentage-based maximum. To enforce dependent insurance coverage limits tied to an employee's elected amount, Workday uses a cross plan insurance percentage maximum, making D the correct configuration choice.