A Biologist Interested in Determining Which Plant Organs (Stems,buds,leaves,etc

A biologist interested in determining which plant organs (stems,buds,leaves,etc.) are responsible for sensing photoperiod might perform which of the following experiments?

A) measure auxin levels in different parts of the plant before and after exposure to light
B) cover different plant organs with a foil covering to prevent light exposure
C) expose the plants to different wavelengths of light
D) remove the apical meristems from different parts of the plant