The correct answer is D) towing connection. Inflatable liferafts are required to be equipped with a towing connection, which allows the liferaft to be towed by a rescue vessel if necessary. This is a crucial safety feature, as it enables the liferaft to be maneuvered and transported to a safe location in the event of an emergency. The other options are incorrect because they do not reflect the standard equipment required for inflatable liferafts. A very pistol is not a standard item, portable radios may be included but are not a universal requirement, and canned milk is not a typical liferaft provision.