Q. Which one of the following categories of animals is correctly described with no single exception in it?
A) All reptiles possess scales, have a three chambered heart and are cold blooded (poikilothermal)
B) All bony fishes have four pairs of gills and an operculum on each side
C) All sponges are marine and have collared cells
D) All mammals are viviparous and possess diaphragm for breathing
Explanation
[Solution from source] Every bony fish has four pairs of gills covered by an operculum on each side. The other groups have exceptions: crocodiles have a four-chambered heart, some sponges (Spongilla) live in freshwater, and monotremes lay eggs. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.