The reaction in which the yield of the product

cannot be increased by the application of high pressure is

(a) PCl 3 (g) + Cl 2 (g) ----reversible sign------>-PCl 5 (g)

(b) N 2 (g) + O 2 (g)-------r-> 2NO (g)

(c) N 2 (g) + 3H 2 (g)-----r--> 2NH 3 (g)

(d) 2SO 2 (g) + O 2 (g) ---r-->2SO 3 (g)

r=reversible reacn arrow

giv explaination