Explanation

(c)
According to Le-Chatelier principle the reactions in which number of moles of reactants is equal to number of moles of products, is not effected by change in pressure.
$2NO(g) \rightleftharpoons N_{2}(g) + O_{2}(g)\$
Moles of reactants =2
Moles of products = 2
$\because$ There is no change in number of moles of reactants and products.
$\because$The reaction is not effected by change in pressure.