An increase in carbon dioxide content in the atmosphere would not cause
(a) more heat to be retained by the environment
(b) increase in photosynthesis in plants
(c) global warming
(d) abundance of desert plants
CO2 is a greenhouse gas thus, its increase will trap more heat and will cause global warming. Also, an increase in CO2 will increase the rate of photosynthesis however, CO2 an increase doesn't contribute towards deserted conditions increase in carbon dioxide content in the atmosphere would not cause an abundance of desert plants as when the temperature rises (due to excessive carbon dioxide emission) their ability to take up carbon dioxide reduces.
Hence, the correct option for this question is option D