Red algae, also known as Rhodophyta, are a group of algae that typically exhibit a red or purplish color due to the presence of pigments such as phycoerythrin. Phycoerythrin is a red pigment that helps red algae absorb light for photosynthesis. Floridean starch is a type of storage carbohydrate found in red algae. It is a unique form of starch that differs from the starch found in other algae and plants. Therefore, the correct answer is (A) Red algae.