Watson and Crick first discovered the structure of the DNA molecule. The structure was described as having a double helical structure. The structure is composed of molecules or bases called nucleotides. The structure was found to have 4 basic nucleotides or base pairs. They are namely adenine, guanine, cytosine and thymine.
Answer: c is the correct answer
Explanation:
The fresh water is in a very big minority when compared to the total amount of water reserves on the planet.
The freshwater accounts for only 2%, while the rest of the 98% are saline water.
But the available freshwater for usage is even less, as from those 2% around 87% is frozen in the ice caps and the glaciers. Around 12% is groundwater, and not all of it is suitable for usage, and only 1% is the freshwater that is the most available from the rivers and the lakes.
This makes the freshwater a prime thing for preservation, as it is what enables the life on the planet, so much more measures have to be undertaken for it to be clean and in healthy condition.
Answer:
foreign molecules in the body