Final answer:
Preexisting sensory deficit in the area to be blocked is considered an absolute contraindication for a nerve block.
Step-by-step explanation:
An absolute contraindication refers to a finding that suggests a nerve block is not recommended under any circumstances. In the given options, the absolute contraindication is D) Preexisting sensory deficit in the area to be blocked. This means that if the patient already has a sensory deficit in the specific area that needs to be blocked, a nerve block is not recommended.