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 mammalsare viviparous and possess diaphragm for breathing