Which of the following acts are considered necessary but may involve a degree of choice?

The act described as necessary but involving a degree of choice aligns with discretionary acts. Discretionary acts are those where the individual or authority has the option to decide on the course of action based on their judgment or preferences. While these acts are often required to ensure safety and compliance, individuals have some latitude in how they are executed, allowing for flexibility in their application.

In practice, this means that an inspector might use discretion when determining the most effective methods for addressing fire safety regulations in a particular scenario. This could include how strictly to enforce certain standards based on the specific circumstances of a building or its occupants.

On the other hand, statutory acts, mandatory acts, and routine acts do not provide such flexibility. Statutory acts are binding laws that must be followed without deviation, while mandatory acts are required actions with no room for personal judgment. Routine acts refer to customary procedures that are generally followed without consideration for individual discretion. Therefore, discretion is the key aspect that makes discretionary acts the correct choice in this context.