What document is used to show loss costs and standardized forms on behalf of member companies?

The correct document used to show loss costs and standardized forms on behalf of member companies is a binder. A binder serves as an interim agreement between the insurer and the insured while the formal policy is being prepared. It provides coverage confirmation and may summarize the terms of the coverage including loss costs. This allows insurers to maintain consistency and standardization across different companies that may be part of an association or pool.

Unlike the policy declaration, which details the specifics of an individual insurance policy for a specific insured, the binder is a more generalized document that represents a temporary contract for insurance. Similarly, a loss report is meant to detail claims or losses that have occurred rather than provide loss costs or standardized forms. The insurance application is a document submitted by an applicant seeking coverage, outlining risk factors and request details, which doesn't directly show loss costs or coverage forms either. Therefore, the binder is the appropriate answer in this context as it best fits the criteria laid out in the question.