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, specifically a hydro-lyase. However, in many simplified biochemistry contexts and older classifications, it is sometimes grouped with isomerases due to its role in the citric acid cycle alongside isomerization steps, but strictly speaking, it is a lyase. Wait, let me double-check standard MCQ banks for this specific question. In many Pakistani medical/biochemistry MCQs, Fumarase is often classified as a Lyase. However, some sources might classify it under Isomerases if they consider the reversible nature or confuse it with other enzymes. Let's look at the options: A: Ligase, B: Isomerases, C: Lysose (likely typo for Lyase), D: Hydrolase. Fumarase is EC 4.2.1.2, which is a Lyase. Option C says 'Lysose', which is likely a typo for 'Lyase'. If the current answer is C and the text is 'Lysose enzyme', it implies Lyase. So C is likely correct. But wait, sometimes Fumarase is considered in the context of Isomerases in some specific curricula? No, standard biochemistry says Lyase. The typo 'Lysose' makes option C suspicious. If 'Lysose' is meant to be 'Lyase', then C is correct. If the current answer is C, and the text is 'Lysose', I should assume it means Lyase. However, some MCQs might have B as the answer if they consider the reversible hydration/dehydration as part of isomerization in a broad sense? No, that's incorrect. Fumarase is definitely a Lyase. The typo 'Lysose' is problematic. If I must choose between Isomerase and Lyase (typoed), Lyase is the scientific truth. So C is likely correct despite the typo. But wait, let me check if there's a trick. Some sources classify Fumarase as an Isomerase in very old texts? No. It's a Lyase. The current answer is C. I will mark it as correct but note the typo. Actually, looking at common MCQs for this, sometimes the answer key says Isomerase due to errors in question banks. But scientifically, it's a Lyase. If the option is 'Lysose', it's almost certainly a typo for Lyase. So C is correct. I will set isCurrentAnswerCorrect to true. Confidence high. Explanation: Fumarase is a lyase enzyme (EC 4.2.1.2) that catalyzes the hydration of fumarate. Option C likely contains a typo for 'Lyase', making it the correct choice scientifically.