The branch of science dealing with the study of birds is

Which invertebrate animals possess a calcium carbonate skeleton?

Match the items in Column-$I$ with Column-$II$ and select the correct option:

Column-$I$	Column-$II$
$(A)$ Fish	$(i)$ Two atria and one ventricle
$(B)$ Frog	$(ii)$ One atrium and one ventricle
$(C)$ Snake	$(iii)$ Two atria and two ventricles
$(D)$ Ostrich	$(iv)$ Two atria and incompletely divided ventricle

Consider the following three statements $(A-C)$ and select the option which includes all the correct ones only:
$(A)$ The earthworm shows metameric segmentation.
$(B)$ Platyhelminthes shows organ level of body organisation.
$(C)$ In Aschelminthes,mesogloea is present between ectoderm and endoderm.

Which of the following pairs is correctly matched?

Which of the following pairs is incorrectly matched?