Which two groups classify vitamins, and which can be toxic if not used properly?

Vitamins are classified into two primary groups: water-soluble and fat-soluble. Water-soluble vitamins include vitamin C and the B vitamins, which are not stored in the body and are excreted through urine when consumed in excess. In contrast, fat-soluble vitamins—such as A, D, E, and K—are stored in the liver and fatty tissues. This storage ability means that these vitamins can accumulate and potentially reach toxic levels if consumed excessively over time.

The correct choice highlights that fat-soluble vitamins are the ones that can be toxic if not used properly. For instance, too much vitamin A can lead to toxicity and cause symptoms like nausea, headache, and even liver damage. Similarly, excessive vitamin D can result in hypercalcemia (high calcium levels), which can be harmful.

The other options do not accurately convey this distinction or misclassify the groups that are relevant to vitamin toxicity. Understanding the differentiation between these two categories is crucial for safe dietary practices and supplementation, reinforcing the importance of proper vitamin use to avoid potential health risks.