Which of the following is a permitted use of the automobile under the SPF#1?

The permitted use of the automobile under the Standard Automobile Policy (SPF#1) includes transporting friends on a "share the trip" basis. This means that if the vehicle is being used to give friends a ride without charging them, it falls within the regular personal use of the automobile as intended by the policy. It emphasizes the personal and social nature of vehicle use that the SPF#1 is designed to cover.

In contrast, other options present uses of the vehicle that are either hazardous or not aligned with the personal use parameters set out in the policy. Transporting radioactive materials or explosives introduces significant risk and legal considerations that typically are not covered under standard auto insurance. Renting out the vehicle represents a commercial use scenario, which is outside the coverage intended for personal vehicles under the SPF#1. Thus, the focus on personal transportation for non-commercial purposes is the key reason why transporting friends on a "share the trip" basis is a permitted use.