Answer:
Answer is D. The substances utilized in response to light are produced in the terminal bud.
Refer below.
Step-by-step explanation:
We know that if you place a houseplant on a windowsill, it will soon orient its leaves toward the light. Turning the plant will cause it to orient its leaves again. Removal of the terminal bud stops this response. Thid is most likely the cause of this "lack of flexibility" The substances utilized in response to light are produced in the terminal bud.