If $F_{pp},F_{nn}$ and $F_{pn}$ denote, respectively, the nuclear forces between two protons, between two neutrons and between a proton and a neutron, then

The correct option is D $F_{nn}=F_{pn}\ne F_{pp}$

$\begin{array}{c}\text{Given}-\ast F_{nn}=\text{Force between two neutrons.}\\ \begin{array}{c}\ast F_{Pp}=\text{Force between two protons.}\\ \ast F_{pn}=\text{Force between neutron and proton.}\end{array}\end{array}$

$\begin{array}{c}\text{Since, neutron is a neutral particle having no net}\\ \text{charge. Hence, the force between neutron-neutron}\\ \text{and neutron-proton is equal.}\\ \text{A proton is a charged particle, and when}\\ \text{two protons tends to approach, the electrostatic}\\ \text{forces repel them and decreases the}\\ \text{proton-proton force.}\end{array}$

$\begin{array}{c}\Rightarrow F_{pp}<F_{Pn}=F_{nn}\\ \text{or}{F}_{pp}\ne F_{pn}=F_{nn}\\ \text{Hence, option}\left(d\right)\text{is correct.}\end{array}$