The correct answer is D — Windstorm. The Commercial Property Causes of Loss — Special Form operates primarily on an open-perils basis. Rather than limiting coverage only to individually listed causes of loss, it generally covers risks of direct physical loss unless the cause is specifically excluded or limited by the form.

The Special Form specifically excludes smog. It also contains a Water exclusion that includes flood, surface water, waves, overflow of bodies of water, mudslide, and mudflow. Consequently, options A, B, and C describe causes specifically removed from the broad Special Form coverage grant.

Windstorm, by contrast, is not generally excluded by the standard Causes of Loss — Special Form. Direct physical damage caused by wind is therefore ordinarily covered unless another exclusion, limitation, endorsement, or property-specific provision applies.

This illustrates an essential adjusting distinction. Under a named-perils form, the insured must establish that the damage resulted from one of the listed covered causes. Under an open-perils Special Form, analysis begins with broad direct physical loss coverage and then determines whether an exclusion or limitation removes the loss.

The Series 17-70 outline specifically covers Commercial Property causes-of-loss forms, exclusions, and open-versus-named-peril concepts.

Therefore, D is correct.