The correct option is B High temperature and low pressure
Given reversible reaction 2SO2(g)+O2(g)⇌2SO3(g), ΔH=+Q cal
We need a low production of SO3 i.e. lower amount of product.
Since ΔH<0
The reaction is exothermic. For a high temperature, the reaction will proceed in backward direction, i.e. the reactant side. So, less SO3 will be formed.
Pressure:
Δng=2−3=−1Δng<0
For a low pressure, the reaction will tend to go that side where number of gaseous moles increase. It increases in backward direction. So, for a low pressure more reactants are formed and less SO3 is formed.