Plants detect and respond to the daily cycle of light and darkness, and potted plants in season include chrysanthemums, daisies and cyclamen. Given these facts, what detects and responds to the daily cycle of light and darkness among the following options:
- chemicals
 - h2o
 - humans
 - goats
 - clouds
 - gravity
 - fens
 - daisies


 

        daisies 