What is the name of the commercial medication preparation of vitamin B1 that paramedics administer to malnourished patients?

The correct option, Thiamine, is the commercially prepared form of vitamin B1 that is administered by paramedics, especially to malnourished patients or those suspected of having Wernicke's encephalopathy. Thiamine plays a crucial role in carbohydrate metabolism and is vital for nerve function. In cases of alcohol abuse or malnutrition, the body may be deficient in thiamine, leading to neurological and cardiovascular issues. Administering thiamine helps to prevent these complications and supports the patients’ recovery.

The other options are different forms of B vitamins, which serve various functions in the body but are not related to the preparation given for vitamin B1 deficiency. Niacin, Riboflavin, and Pyridoxine each have specific roles, such as energy metabolism and red blood cell production, but they do not address the needs associated with thiamine deficiency. This context makes clear why Thiamine is the appropriate choice for this particular scenario.