The right answer to this question is option C. the traits acted upon natural selection were genes.
At the time Charles Darwin developed the evolution theory, there wasn't a single study about genes in all science scenery, that could be explained by the lack of technology to study them and even to know they existed in the first place.
So, his theory was basically talking about adaptation, if an organism can't survive a specific environment, he'll probably die until another generation comes in and this one can survive in this environment, passing their genes to the next ones. The lack of information was the knowledge about the genes we have today, that's why most scientists take only the new Darwin theory, that includes the study of genes.
The acids have more H+ while bases have more OH-. About pH, typically under room temperature, when a solution has pH<7, it is acid. When pH>7, it is base. And when pH=7, it is neutral.
The answer is mutualism or letter a. The tick birds ride on the buffalo’s back and
eats the tick from its body. This
relieves the buffalo from the insects that suck on its blood. The birds have a food source while the buffalo has someone to
eat away at the ticks.
The universe began about 14 billion years ago. Or 13.7 billion
B - the food it obtains!
Hope that helps!