Answer: B. A community interaction
Answer: alternative A
Explanation: The deeper the layer in water, the <u>less light reaches it</u>. In deeper layers, therefore, it becomes difficult, if not impossible, to photosynthesis to occur. Having in mind that <u>phytoplankton and photosynthetic organisms depend on photosynthesis to survive,</u> they won't appear in such dephts.
The correct answer is d. spinal cord.
Spinal cord is a bundle of neurons which starts from the brain and runs down the entire length of the back of the body. The spinal cord acts as a main means to transmit the messages between the brain and the body.
Sensory or efferent neurons carry the information from the perimeter of the body and pass to the central nervous system whereas the motor or efferent neurons act as a communication channel and carry the information from the nervous system to various glands and muscles.