The answer is Compound light microscope.
Among mentioned types of microscopes, only a compound light microscope enables a study of the living specimen. Therefore, the best microscope to view living single-celled organisms in a sample of pond water is the compound light microscope. Electron microscopes are very expensive and with a great magnification, up to 1,000,000 times, they are better for some structures on the cell membranes. The compound light microscope has a magnification up to 1,500 times while dissecting microscope has a magnification up to 75 times which is not enough for studying single-celled organisms.