As a result of a positive PPD and negative chest x-ray, you prescribe INH. Because of a possible side effect associated with this therapy, which of the following supplementary nutritional agents should be added.

A. Vitamin B12 (cyanocobalamin): Vitamin B12 is essential for red blood cell production and neurologic function, but it is not affected by isoniazid therapy. Isoniazid does not interfere with B12 absorption or metabolism, so supplementation with B12 is not routinely indicated in patients receiving INH for latent tuberculosis. B. Vitamin B3 (niacin): Niacin plays a role in energy metabolism and DNA repair, but it is not directly impacted by isoniazid therapy. INH does not cause niacin deficiency, and routine supplementation with niacin is not recommended as part of standard latent TB treatment protocols. C. Vitamin B6 (pyridoxine): Isoniazid inhibits pyridoxine metabolism, which can lead to peripheral neuropathy, particularly in individuals at higher risk such as malnourished patients, pregnant women, or those with diabetes. Supplementing with vitamin B6 helps prevent neuropathic symptoms by restoring normal coenzyme function in neurotransmitter synthesis and nerve health. D. Vitamin B9 (folate): Folate is essential for DNA synthesis and red blood cell formation, but isoniazid therapy does not induce folate deficiency. Routine folate supplementation is not indicated specifically for patients receiving INH unless there is an unrelated deficiency or concurrent risk factor for folate depletion.