The correct option is D Rhodospirillum
Anoxygenic photosynthesis is a process where light energy is captured and converted to ATP. Here water is not used as an electron donor and hence oxygen is not released. So, it is called anoxygenic. Example: Rhodospirillum.
Spirogyra, Chlamydomonas and Ulva undergo oxygenic photosynthesis, in which oxygen is released due to splitting of water.