The correct option is A Cladophora
The reticulated filamentous green algae-Cladophora placed in a suspension of aerobic bacteria was used for the experiment as the experimental material by T.W. Englemann. He used a prism to split light into its components which he used to illuminate a suspension of aerobic bacteria containing Cladophora. These bacteria helped in detection of sites where oxygen was evolved. These bacteria accumulated mainly at red and blue light of the spectrum. Thus, the first action spectrum (a graph of the rate of any physiological activity such as photosynthesis plotted against wavelength of light) of photosynthesis was described.
Ulothrix is an example of non-branching filamentous green algae.
Vaucheria is an example of yellow green algae.
Spirogyra is a filamentous green alga.