The correct options are
A it maintains ecological balance.
B it sustains life.
C it is necessary for respiration in aquatic organisms.
D it is essential for photosynthesis.
∙ Water maintains all the ecosystems on earth.
∙ It is considered as an universal solvent.
∙ It provides the nutrients and minerals necessary to sustain physical life.
∙ The water bodies contain dissolved air (oxygen) which is necessary for respiration in aquatic organisms.
∙ It is essential for the growth of the plants and essential to carry out photosynthesis (process by which plants make their food).