Which of the following causes of loss is covered under a commercial property basic form?

In a commercial property basic form, coverage is typically designed to protect against a specific range of perils. Volcanic eruption is included as a named peril within these policies, making it a covered cause of loss.

This inclusion means that if a volcanic eruption occurs and causes damage to the insured property, the policy would respond to cover the losses associated with that event. It's essential to understand that the basic form is typically limited to certain perils and does not encompass all potential risks.

On the other hand, nuclear hazard is usually excluded from coverage due to the high risks associated with such events. Dry rot, typically considered a maintenance issue, also falls outside the coverage as it’s often seen as resulting from inadequate upkeep rather than a sudden or accidental cause of loss. Earth movement, which generally encompasses earthquakes and similar events, is often excluded in basic forms due to the significant risk and potential for widespread damage. Thus, volcanic eruption stands out as the correct choice, being explicitly covered under the terms of a commercial property basic form.