Which of the following catalytic processes involves a homogeneous catalyst?
The hydrogenation of liquid vegetable oils using a solid nickel catalyst
The reaction between CO\text{CO}CO and NO\text{NO}NO gases in a catalytic converter containing platinum
The esterification of ethanoic acid and ethanol using a liquid concentrated sulfuric acid catalyst
The synthesis of SO3\text{SO}_3SO3 gas from SO2\text{SO}_2SO2 gas in the Contact process using solid V2O5\text{V}_2\text{O}_5V2O5
