A star initially has $\;10^{4}\;$ deuterons . It produces energy via the process $\;_{1}H^{2}+_{1}H^{2} \to _{1}H^{3}+P\;$ and $\;_{1}H^{2}+_{1}H^{3} \to _{2}He^{4}+n\;$ If average power radiated by star is $\;10^{16} W\;$ the deutron supply of star is exhausted in a time of order of

Question

$(a)\;10^{11} s\qquad(b)\;10^{12} s\qquad(c)\;10^{13} s\qquad(d)\;10^{14} s$