Some algae have chloroplasts and chlorophyll and obtain their energy through photosynthesis while some algae like euglena are both heterotrophic (decompose dead organic matter) and autotrophic (use photosynthesis) and can also obtain energy likewise.
B. Controlling the flow of Blood to the skin seems to make the most sense
A frog gets rid of it's urine through the kidneys because the heart pumps blood throughout the body, the lungs are used to take in O2 molecules and gills are use to filter out the hydrogen in HO2 so they can breathe under water. However the kidneys are part of the waste disposal system (what makes us need trip to the bathroom ever now and then) therefore that is the answer.<span />
