It means they constantly interact with each other and with their environment and are dependent upon each other for survival.
Hope this helps you out :)
D identical diploid daughter cells
Limestone.
It is a sedimentary rock composed of calcite and aragonite. It is used as a building material mainly because it is easily available and easy to work with.
Limestone is used in the manufacture of steel as it is the primary raw material that helps to remove impurities from the iron ore and produces waste matter that has low melting point and viscosity
A,b I think should be the answer
D : the shape of a solid does not change when it is put into a container
