Final answer:
The appropriate action for a leaking safety valve is to have it repaired or replaced, as it is a critical safety component. Adjusting the spring or ignoring the leakage is not advisable and poses a risk.
Step-by-step explanation:
When a safety valve leaks at a pressure less than that at which it is set to open, this is a sign that the valve may not be functioning properly. This could be a serious safety concern, as safety valves are critical components in preventing equipment failures due to overpressure. The correct action in this scenario would be option (c): have valve repaired or replaced.
Adjusting the tension on the spring (option a) without understanding the root cause of the leakage can be dangerous and could lead to valve malfunction during a real overpressure condition. Repeatedly opening and closing the valve (option b) might seem like a temporary solution, but it does not address the underlying issue and may further damage the valve seat. Lastly, it is important to note that option (d), which suggests that it doesn't matter if a safety valve leaks, is incorrect; any leakage from a safety valve should be taken seriously and dealt with promptly, as it pertains to the safety of the entire system.