Explanation

Fumarase (fumarate hydratase) catalyzes the reversible hydration of fumarate to malate. This reaction involves adding water across a double bond, which classifies it as a lyase enzyme. However, in many simplified biochemical contexts and older classifications, it is sometimes grouped with isomerases due to its role in the citric acid cycle's stereospecific transformations, or more accurately, it is a Lyase (EC 4.2.1.2). Wait, let me double-check. Fumarase adds H2O to fumarate. EC 4.2.1.2 is Fumarate hydratase. Class 4 is Lyases. So C 'Lysose' (likely typo for Lyase) is actually the correct class. The option says 'Lysose enzyme'. Is 'Lysose' a typo for 'Lyase'? Yes. If the option meant Lyase, then C is correct. If the option meant something else, it's wrong. Given standard MCQ patterns, 'Lysose' is almost certainly a typo for 'Lyase'. Therefore, the current answer C is likely correct despite the typo. I should flag the typo but confirm C is the intended answer. Actually, let's look at B: Isomerases. Fumarase does not change the molecular formula, it adds water. So it's not an isomerase. It's a lyase (specifically hydro-lyase). So C is correct if 'Lysose' = 'Lyase'. I will assume C is correct and note the typo.