Buffers are because of low tolerance to changes in ph. a. critical to biological systems because of low b. present in our blood stream c. usually mada dally made up of a weak acid and its conjugate ban d. essential in all bodies of water that contain life. e. all of the above are true.

The correct answer is option'e':All of the options are correct

Explanation:

A buffer solution is a solution that resists a change in it's pH and is formed by mixing a weak acid and it's conjugate base or by mixing a weak base and it's conjugate acid.

In blood stream a buffer of carbonic acid and bicarbonate anion this maintaining pH in the blood stream.

Buffers are present in many biological systems such as blood, phosphate buffer, hemoglobin buffer,e.t.c.

Thus a buffer is essential in water bodies such as lakes resisting a change in pH and the buffer is formed by dissolved carbon dioxide.