To solve this problem, we need to identify the most abundant protein in animals from the given options. Let's analyze each option:$\newline \bullet$Collagen:$\newline$ - Collagen is a structural protein found in connective tissues such as skin, tendons, ligaments, and bones.$\newline$ - It provides strength and elasticity to these tissues.$\newline$ - Collagen is known to be the most abundant protein in mammals, making up about 25-35\% of the whole-body protein content.$\newline \bullet$Lectin:$\newline$ - Lectins are a type of protein that can bind to carbohydrates.$\newline$ - They are not as abundant as structural proteins like collagen.$\newline \bullet$Insulin:$\newline$ - Insulin is a hormone produced by the pancreas that regulates blood glucose levels.$\newline$ - It is not a structural protein and is present in much smaller quantities compared to collagen.$\newline \bullet$Haemoglobin:$\newline$ - Haemoglobin is a protein found in red blood cells that is responsible for oxygen transport.$\newline$ - While it is abundant in red blood cells, it is not as abundant as collagen in the overall protein content of the body.$\newline$Based on the analysis, collagen is the most abundant protein in animals.$\newline$Therefore, the correct answer is Option 1: Collagen.