Answer:The correct answer is option :
'It is in a different phase than the reactants'.
Step-by-step explanation:
Catalyst are those chemical substance which effect the speed of the reaction.
There are two types of catalyst :
Heterogeneous catalyst are the catalysis in which catalyst are present in different phase from the reactants and the products.
Homogeneous catalyst are the catalysis in which catalyst are present in same phase as that of the reactants and the products.