Which of the following is true about photosynthetic bacteria?

A) They are the most primitive of all bacteria.
B) Photosynthesis appears to have evolved several separate times.
C) Photosynthetic bacteria all appear to be closely related.
D) A comparison of rRNA genes in different lineages of photosynthetic bacteria would reveal that the genes are almost identical in all lineages.
E) All photosynthetic bacteria appear to have evolved relatively recently.