Which of the following is not a part of Amitav Ghosh’s Ibis trilogy?

The correct option is The Calcutta Chromosome.

To understand why this is the correct answer, let us break down Amitav Ghosh's literary works and look at the composition of his famous Ibis trilogy:
1. Sea of Poppies (published in 2008) is the first novel of the Ibis trilogy. It introduces the main characters and sets the stage on the schooner Ibis before the First Opium War.
2. River of Smoke (published in 2011) is the second novel of the trilogy, continuing the journey and focusing heavily on the opium trade in Canton (Guangzhou).
3. Flood of Fire (published in 2015) is the third and final installment of the trilogy, detailing the outbreak of the First Opium War and its aftermath.

The Calcutta Chromosome (published in 1995), on the other hand, is a self-contained medical thriller/science fiction novel by Amitav Ghosh that deals with malaria research and is completely separate from the historical narrative of the Ibis trilogy.