To solve this problem, we need to evaluate each statement to determine which one is incorrect.$\newline$Let's analyze each option:$\newline$• Option 1: Ovalbumin is a simple food reserve in egg-white.$\newline$ - Ovalbumin is indeed a protein found in egg white and serves as a source of amino acids for the developing embryo.$\newline$ - This statement is correct.$\newline$• Option 2: Blood proteins thrombin and fibrinogen are involved in blood clotting.$\newline$ - Thrombin and fibrinogen are key proteins in the blood clotting process. Thrombin converts fibrinogen into fibrin, which forms a clot.$\newline$ - This statement is correct.$\newline$• Option 3: Denaturation makes the proteins more active.$\newline$ - Denaturation involves the unfolding of a protein's structure, leading to loss of its biological activity.$\newline$ - This statement is incorrect because denaturation typically makes proteins less active or inactive.$\newline$• Option 4: Insulin maintains sugar level in the blood of a human body.$\newline$ - Insulin is a hormone that regulates blood glucose levels by facilitating the uptake of glucose into cells.$\newline$ - This statement is correct.$\newline$Therefore, the statement that is not correct is Option 3: Denaturation makes the proteins more active.