Which of the following substances generally has the highest melting point?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Experimental reaction of $CH_{3}Cl$ with aniline and anhydrous $AlCl_{3}$ does not give $o-$ and $p-$methylaniline.
Reason $(R)$: The $-NH_{2}$ group of aniline becomes deactivating because of salt formation with anhydrous $AlCl_{3}$ and hence yields $m-$methylaniline as the product.
In the light of the above statements,choose the most appropriate answer from the options given below.

What is the correct order of basic strength in substituted amines in an aqueous solution?

Which of the following is the least basic?

What is the product of the following reaction?

Consider the following sequence of reactions. Total number of $sp^{3}$ hybridised carbon atoms in the major product $C$ formed is . . . . . . .