• Vitamin B12 Deficiency: Vitamin B12 is crucial for DNA synthesis. A deficiency leads to the production of large, abnormal red blood cell precursors (megaloblasts) in the bone marrow, resulting in megaloblastic anemia.
• Folic Acid Deficiency: Similar to Vitamin B12, folic acid (folate) is essential for DNA synthesis and red blood cell maturation. A deficiency also results in the formation of megaloblasts and consequently megaloblastic anemia.

Therefore, the correct answer is:

• Both Vitamin B 12 Deficiency and Folic Acid Deficiency

Martinus Beijerinck (1851–1931), a Dutch microbiologist, is recognized as the “Father of Virology” for his groundbreaking work on the tobacco mosaic virus in 1898. He demonstrated that the infectious agent (later termed a virus) could pass through filters that trapped bacteria and required living host cells to replicate, establishing viruses as distinct entities.

Why not the others?

• Robert Koch: Founded bacteriology (Koch’s postulates for linking microbes to disease).

• Louis Pasteur: Pioneered germ theory and vaccines (rabies, anthrax), but focused on bacteria, not viruses.

• Antony van Leeuwenhoek: Discovered bacteria using microscopes in the 17th century, long before viruses were identified.

• Red Blood Cells (RBCs) in urine are primarily detected by microscopic examination of the urine sediment.

• Physical examination may suggest hematuria if urine appears red or smoky.

• Chemical examination (e.g., dipstick) can indicate the presence of blood but does not confirm if it’s RBCs, hemoglobin, or myoglobin.

• Microscopic examination confirms the presence and morphology of RBCs, which is critical for diagnosis.

To examine parasitic cysts (e.g., protozoan cysts like Giardia, Entamoeba) under a microscope, the following are commonly used:

1. Iodine Preparation (Lugol’s Iodine or D’Antoni’s Iodine)
   • Stains cysts brown-yellow, highlighting nuclei, glycogen masses, and chromatoid bodies.
   • Provides better visualization of internal structures compared to unstained wet mounts.
2. Normal Saline (Wet Mount)
   • Used for motile trophozoites (live parasites) but does not stain cysts.

Incorrect Options:

• Z-N Stain (Ziehl-Neelsen) → Used for acid-fast bacteria (e.g., Mycobacterium).
• Gram Stain → Used for bacterial classification, not parasites.

Thus, iodine preparation is the best choice for examining parasitic cysts under a microscope.