Answer
B.
Work Step by Step
The chloroplasts of brown algae show evidence of their origin from the endosymbiosis of a red alga (an extra/fourth membrane, similarity to the chloroplasts of red algae; B.). C. mentions even fewer membranes than are found in green or red algae's chloroplasts, and A. contradicts the existing evidence, while D. can be excluded since the red and green algae have similar chloroplasts.
