Answer
B. acid + base --> salt + water
Explanation
Acids are substances that dissolve in water to produce hydrogen ions, H+.A base is a substance that dissolves in water to produce hydroxide ions, OH-.In a chemical reaction of an acid and a base, the products are a salt and water.For example when hydrocholoric acid is added to sodium hydroxide, a salt namely sodium chloride is formed with additional water.
Answer:
The answer will be C. Variable
Explanation:
The answer will be C because A response is a reactant for the plant and the question is asking about the light. B is incorrect because stimulus is how a plant reacts to nature for example gravitrophism and thingatropism also its asking about the light not the plant. D is incorrect because... come on now does it even make sense XD
Hope this helps

Actually Welcome to the concept of Bond Formation.
Answer is :-
B.) O and Cl
These both are Non-Metals with high Electronegativity nature, hence none of them can share electrons to foram any bond to eventually form a Electro valentines Compound.