(B) The total energy of a particle is given by $E = V + K$,where $V$ is the potential energy and $K$ is the kinetic energy. Since $K = E - V$ and kinetic energy $K$ must always be non-negative $(K \ge 0)$,a particle can exist in a region only if $E - V \ge 0$,which implies $V \le E$.
$1.$ Region $A$ $(V > E)$: Here,$K = E - V < 0$. Since kinetic energy cannot be negative,the particle cannot be found in this region.
$2.$ Region $B$ $(V < E)$: Here,$K = E - V > 0$. Since kinetic energy is positive,the particle can be found in this region.
$3.$ Region $C$ $(K < E)$: Since $K = E - V$,the condition $K < E$ implies $E - V < E$,which simplifies to $V > 0$. As long as the potential energy $V$ is positive,this condition is satisfied. Thus,the particle can be found in this region.
$4.$ Region $D$ $(V > E)$: Similar to region $A$,here $K = E - V < 0$. Since kinetic energy cannot be negative,the particle cannot be found in this region.