The barnacles are only able to attach them selfs to surfaces in the water. Since the surface is limited, barnacles are attaching themselves to the other barnacles, crowding the rock. The muscles were not able to grow or attach themselves off the surface of the rock. Same thing with the mussels that are growing on the rock. So not only barnacles are crowding the rock, but Mussels as well are crowding the rock.
Answer: C). Sensory neurons, D).motor neurons
Explanation: Sensory neurons are nerve cells that carry signals from the external parts of the body such as the skin, eyes, ear, nose (the sense organs) to the brain.
Motor neurons are nerve cells that carry information or messages away from the central nervous system ( brain and spinal cord) to the rest of the body such as the skin, muscles and glands.
What Mendel did according to the illustration would be called test-crossing.
<h3>Test-crossing</h3>
In genetics, test crossing is a procedure through which the zygosity of an individual can be determined - whether it is homzygous or heterozygous.
Test crossing requires that an organism who displays a dominant trait but whose zygosity is unknown is crossed with another organism of the same species but who displays the recessive version of the same trait.
By so doing and using the knowledge of probability, the resulting offspring from the cross will be used to determine the zygosity level of the parent.
More on test crossing can be found here: brainly.com/question/16805498
