Recent work in classification of life on earth has shown that what were once called prokaryotes are much more diverse than ever suspected. the prokaryotae are now divided into two domains, the eubacteria and the archaeabacteria, as different from each other as either is from the eukaryota. no one of these groups is ancestral to the others, and each shares certain features with the others as well as having its own unique characteristics. one group of prokaryotae, the blue-green algae, have left a fossil record that is dated to be nearly 3.5 billion years old, among the oldest fossils currently known. these blue-green algae had cell walls and were photosynthetic. considering this, where would you place the cyanobacteria in this cladogram?

a) archaebacteria
b) eubacteria
c) plantae
d) protista