**Core Concept**
Vitamin B12 deficiency can lead to severe anemia due to impaired DNA synthesis and red blood cell production. Parenteral administration of Vitamin B12 is necessary in cases of severe deficiency or inability to absorb orally.

**Why the Correct Answer is Right**
Intramuscular (IM) administration of Vitamin B12 is the preferred route for treating severe anemia. This is because IM injections allow for slower release of the vitamin, providing a sustained increase in serum levels. Additionally, IM injections can bypass the gastrointestinal tract, which is often the site of Vitamin B12 deficiency. The methylcobalamin or hydroxocobalamin form of Vitamin B12 is commonly used for IM injections.

**Why Each Wrong Option is Incorrect**
**Option A:** Oral administration of Vitamin B12 may be ineffective in severe cases due to malabsorption issues. It is often used for maintenance therapy in patients with normal absorption.
**Option B:** Subcutaneous injections of Vitamin B12 may not provide the same level of efficacy as IM injections due to faster absorption and shorter duration of action.
**Option C:** Intravenous (IV) administration of Vitamin B12 is generally not necessary unless there is a specific indication for IV therapy, such as severe malabsorption or rapid correction of deficiency.

**Clinical Pearl / High-Yield Fact**
Intramuscular injections of Vitamin B12 should be given in the deltoid muscle for patients under 60 years and in the gluteal muscle for patients over 60 years to minimize the risk of nerve damage.

**Correct Answer: C. Intramuscular (IM) administration of Vitamin B12 is the preferred route for treating severe anemia.