**Core Concept**
The question requires the identification of the malaria parasite species based on the characteristics of the schizonts and the pigment. Malaria parasites exhibit distinct morphological features that can help in their identification, including the size of the schizonts, the number of merozoites, and the color of the pigment.

**Why the Correct Answer is Right**
Plasmodium vivax is characterized by the presence of schizonts measuring 9-10 microns in diameter, which contain 20-24 merozoites. The pigment in P. vivax is yellowish-brown due to the presence of hemozoin, a byproduct of hemoglobin degradation. The schizonts of P. vivax are also larger than those of other Plasmodium species, which can help in distinguishing it from other species. The presence of these characteristic features in the patient's peripheral blood film is consistent with P. vivax infection.

**Why Each Wrong Option is Incorrect**
**Option B:** Plasmodium falciparum typically has smaller schizonts, usually less than 6 microns in diameter, and contains fewer merozoites (8-12). The pigment in P. falciparum is also smaller and more compact.

**Option C:** Plasmodium malariae has larger schizonts, typically 12-18 microns in diameter, and contains 6-8 merozoites. The pigment in P. malariae is also larger and more diffuse.

**Option D:** Plasmodium ovale has smaller schizonts, usually less than 6 microns in diameter, and contains 6-8 merozoites. The pigment in P. ovale is also smaller and more compact.

**Clinical Pearl / High-Yield Fact**
It is essential to note that P. vivax can relapse due to the presence of hypnozoites in the liver, which can reactivate after a period of dormancy. This can lead to a delay in the diagnosis and treatment of P. vivax infection.

**✓ Correct Answer: A. Pl vivax**