Which of the following dwelling policies insured a structure on an actual cash value basis?

The DP-1 dwelling policy, also known as the Basic Form, insures properties on an actual cash value (ACV) basis. This means that in the event of a loss, the insurer will compensate the policyholder for the current replacement cost of the property, minus depreciation. This method reflects the reduction in value over time due to factors like wear and tear or obsolescence, which is fundamental to understanding how claims are settled under this policy.

In contrast, the other options typically involve different valuation methods or coverages. For instance, the HO-3 and HO-6 (homeowner policies) generally provide coverage on a replacement cost basis for the dwelling, which does not factor in depreciation when determining claim payouts. The DP-3 provides more comprehensive coverage, also typically on a replacement cost basis, but with broader perils insured. Therefore, the DP-1 is uniquely characterized by its actual cash value approach, making it the correct answer in this scenario.