Q.12 The extinction of passenger pigeon was due to

1. Increased number of predatory birds

2. Overexploitation by humans

3. Noi-availability of the food

4. Bird flu virus inferior

Ans. (b) The extinction of passenger pigeon (Ectopistes migratorius) was due to the overexploitation of human beings. Factors like an increase in the number of predatory birds, non-availability of food, and bird flu virus infection did not contribute to the extinction of passenger pigeons.
Page 265, XII NCERT