If you share a car with your spouse who uses it frequently, do you have reliable transportation?

The most appropriate answer is that sharing a car with your spouse who uses it frequently may interfere with your schedule. This implies that while the car is available to you, its frequent use by another person introduces uncertainty in accessibility that could impact your transportation reliability. Having reliable transportation typically means having consistent access to a vehicle when needed, and sharing it can lead to scheduling conflicts and delays, depending on your spouse's usage patterns.

The other options suggest scenarios where you might still consider the arrangement reliable, but they overlook the fundamental issue of potential conflicts and access limitations that are inherent when sharing a vehicle frequently. Reliability in this context hinges on consistent availability, which is compromised when one party has dominant use of the vehicle.