322.15
49°C + 273.15= 322.15K
The answer for your question is A.
Natural selection is the process by which individuals who are best suited to the environment tend to leave (on average) more offspring than others.
Evolutionary changes take place over many generations and through millions of years of natural selection. For the genes to survive, they must be among the strongest.
If you are adding something to the water the concentration of water would drop, as it would start off as 100% water but then with the addition of another substance it would change that from 100% free to x% free, due to the water dissolving the substance.