The correct option is B E.coli
Yeast, Ulothrix and plants are eukaryotes. They have special membrane bound organelles, one of which is the mitochondria.
Krebs cycle can be defined as a stepwise, oxidative and cyclic degradation of acetyl CoA derived from the end product of glycolysis i.e. pyruvate. Krebs cycle occurs in the mitochondria in eukaryotes.
E.coli are prokaryotes. They do not have special membrane bound organelles. Hence Krebs' cycle takes place in the cytoplasm.