Photochemical smog: a. is sometimes called london-type smog. b. was more prevalent in the 1800s than the 1900s. c. is caused primarily by industrial emissions. d. is formed from chemical reactions involving sunlight, nitrogen oxides and hydrocarbons. e. is generally worse during the winter months.

Which statement is the best summary of the model? a-a series of aerobic and anaerobic reactions take place in cells b- the sun's energy moves through trophic levels in a food chain c-light energy is converted into stored chemical energy plants. d- food molecules are broken down in the cells if living things.