Which of these is considered to be an unfair claims settlement practice?

An insurer denying claims without fully investigating is indeed considered an unfair claims settlement practice because it undermines the policyholder's right to a fair assessment of their claim. Insurers have a duty to conduct thorough investigations to evaluate the validity of claims properly. When they deny a claim without fully understanding the circumstances or gathering all necessary evidence, it constitutes a breach of this duty, potentially harming the policyholder by wrongfully denying them benefits they are entitled to under the policy.

In the context of claims practices, fair treatment of policyholders requires insurers to adhere to established processes that ensure every claim is evaluated on its merits, which includes a comprehensive and unbiased investigation. By not doing so, insurers may not only violate ethical standards but also regulatory requirements that are in place to protect consumers.

The other situations, while they also reflect negative practices, do not capture the distinct violation of conducting a proper investigation during the claims process as effectively as the correct answer does.