## **Core Concept**
The question tests knowledge on vitamin deficiencies and their associated clinical manifestations, specifically glossitis (inflammation of the tongue) and cheilosis (inflammation of the lips).

## **Why the Correct Answer is Right**
Vitamin B2, also known as riboflavin, plays a crucial role in energy production and can affect skin and mucous membrane health. A deficiency in riboflavin leads to **glossitis** (inflammation of the tongue) and **cheilosis** (inflammation of the lips), among other symptoms. Riboflavin is essential for maintaining the health of mucous membranes and skin.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not correspond to the correct vitamin associated with glossitis and cheilosis.
- **Option C:** This option is incorrect because, although some B vitamins can cause similar symptoms, they are not specifically linked to glossitis and cheilosis as directly as riboflavin (Vitamin B2).
- **Option D:** This option is incorrect because it does not accurately represent the vitamin deficiency associated with the described symptoms.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that riboflavin deficiency often presents with **ocular and oral manifestations**, including cheilosis (fissured lips), glossitis (magenta tongue), and seborrheic dermatitis-like skin lesions. Recognizing these symptoms can help in the early diagnosis and treatment of riboflavin deficiency.

## **Correct Answer:** B. Riboflavin (Vitamin B2).