Adifference between electron transport in photosynthesis and respiration is that in photosynthesis

This difference between electron transport has to do with the source of energy in each respective process. While they both need to force the electrons to the top of the electron chain, photosynthesis uses energy from sunlight while cellular respiration uses food molecules (which provide energy after being oxidized). 

Its either a) or b),wind and water erosion gradually widen the canyon