Not to be too picky, but the question ought to say a positively charge ion rather than atom.
I will assume that is what you mean. An ion, using ordinary means, will be positive if it loses electrons (which are negative).
An ion can never gain protons. Left alone, the nucleus will remain unchanged for the rest of eternity. D is wrong.
C is wrong. If electrons are gained, the ion will go negative.
B is wrong for the same reason D is. An ion can't gain protons and it can't lose them.
A is the answer.
A cell can be thought of as a "factory," with different departments each performing specialized tasks.
If a substance is very sour and has a ph of 4, then you would expect the litmus paper to turn into the shade of red. A substance that is sour and has a pH level that is below 7 would indicate that the substance is an acid or has acidic properties. For an acidic solution, the litmus would be red in color. If a blue litmus paper is used, then it would turn into red while if a red litmus paper is used, then it would remain as red. There is also a general type of litmus paper where the color change range from violet to red. A litmus is widely used in distinguishing acid and bases. It can be used in liquid solutions and in gas mixtures. <span />
The population of carnivore will decline