Which rationale correctly explains the reason for administering injections of vitamin B12 to patients with pernicious anemia?

A. B12 is a mineral for strong bones: B12 is a vitamin, not a mineral, and its primary role is in DNA synthesis and nerve function, not bone structure. B. B12 is found in very small quantities: While true, this doesn't explain why injections are needed instead of oral supplements. C. The patient may lack the intrinsic factor: Pernicious anemia is caused by a lack of intrinsic factor (secreted by the stomach), which is required to absorb Vitamin B12 in the small intestine. Therefore, B12 must be given via injection to bypass the digestive tract. D. The body does not normally manufacture B12: The human body never manufactures B12 (it must come from diet); the issue in pernicious anemia is the inability to absorb it.