The answer to this question would be: d) flushing
Niacin or nicotinic acid is also known as vitamin B3. Niacin has a role in lipid metabolism and consuming a high dose of niacin can lower LDL, lower triglyceride and increase HDL. Therefore, niacin can be used to improve lipid profile. The symptomps of toxicity should be flushing or hepatotoxicity.