<span>Commensalism describes the relationship between humans and most of the normal microbiota that live on our human skin. Commensalism describes a relationship between two living organisms. One organism benefits from the other by gaining things such as food and shelter. from the host organism. The host organism does not gain anything, but it is not harmed in any way either.</span>
Answer;
-Periodic Duty
Explanation;
Duty considered as generic term, for example, can be classified as continuous duty, short-time duty or periodic duty.
-Intermittent periodic duty is a sequence of identical duty cycles, each including a time of operation at constant load and a time de-energized and at rest. The contribution to the temperature-rise given by the starting phase is negligible.
The correct option is: GRATINIC ROCK IN THE OCEAN FLOOR.
Sea floor spreading refers to the process by which molten materials add new oceanic crust to the ocean floor. This process occurs slowly across the earth's middle ocean ridges. Harry Hess formulated an hypothesis to explain the phenomenon of sea floor spreading and all the above options support his hypothesis with the exception of option C.