The correct option is
B BatrachospermumBatrachospermum is one of the fresh water forms of Rhodophyceae. This alga is found in slow running shallow streams and on the banks of lakes and ponds. The alga is also known as the frog spawn or the eggs of frog, because the plants are mucilaginous, moniliform or beaded in appearance to the naked eye.
So, the correct answer is 'Batrachospermum'