Nucleophilic substitution reactions generally expressed as `Nu^(-) +R-L rarr R-Nu +L^(-)` Where `Nu^(-) rarr` Nucleophile , `R-L rarr` substrate, `L rarr` leaving group The best leaving groups are those that become the most stable ions after they depart. since most leaving group leave as a negatibe ion, the best leaving groups are those ions that stabilize a negative charge most effectively. A good leaving group should be (a) electron-withdrawing to polarize the carbon (b) stable once it has left (not a strong base) (c) polaristable to maintain partial bonding with the carbon in the transition state (both `S_(N)1` and `S_(N)2)`. This bonding helps to stabilise the transition state and reduces the activation energy. Among the following which is feasible?A. `X^(-) +CH_(3) -CH_(2)-H rarr CH_(3)-CH_(2)-X +H^(-)`B. `X^(-)+CH_(3)-OH rarr CH_(3)-X +overset(bar(O)H)`C. `X^(-) +H_(3)C -underset(H)underset(|)overset(o+)(OH)rarr CH_(3)-X +H_(2)O`D. `X^(-)+CH_(3)-CH_(3)rarr CH_(3)-X +overset(bar(CH_(3)))`