Proper treatment of experimental subjects helps to ensure which of the following

option a and d is the correct answer

i hope this u

plz mark as the brainliest answer

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

the tricuspid valve is present between right atrium and right ventricle

the correct answer is 2 and 4