Hint: Acidity and basicity of substance depend upon some special properties like basic substances are those substances that have the tendency to accept electrons, have pH value greater than 7, and are bitter in taste.
Complete step by step answer: The compounds given in the question are amines and amines can be defined as those compounds which contain a basic nitrogen atom with lone pair. These are derivatives of ammonia in which one or more hydrogen groups are replaced with an alkyl or aryl group. The basicity of amines varies by the molecule and mainly depends upon the presence of the number of lone pairs. Out of the options given benzylamine is more basic because the benzyl group is an electron-donating group in nature due to the presence of +I effect, therefore, it is able to increase the electron density of nitrogen in the amine group. Thus due to the higher electron density rate of donation of a free pair of electrons is increased due to which basic character is higher in this. On the other hand, phenyl and nitro groups are electron-withdrawing groups so they are able to decrease the electron density of nitrogen of the amine group so as a result, these are less basic in nature. So, the correct answer is “Option D”.
Note: There are basically two types of amines known as aliphatic or aromatic amines which further categorized into primary, secondary, tertiary, and quaternary amines. Like ammonia, amines are also basic in nature.