To solve this problem, we need to identify the animal groups that possess all the given characteristics:$\newline \bullet$(a) Organ system level of organisation$\newline \bullet$(b) Bilateral symmetry$\newline \bullet$(c) True coelomates with segmentation of body$\newline$Let's analyze each option:$\newline \bullet$Option 1: Annelida, Arthropoda and Chordata$\newline$ - Annelida: They have an organ system level of organisation, bilateral symmetry, and are true coelomates with segmented bodies.$\newline$ - Arthropoda: They also possess an organ system level of organisation, bilateral symmetry, and are true coelomates with segmented bodies.$\newline$ - Chordata: They have an organ system level of organisation, bilateral symmetry, and are true coelomates. Many chordates, like vertebrates, show segmentation (e.g., vertebral column).$\newline$ - Therefore, all three groups in Option 1 meet the criteria.$\newline \bullet$Option 2: Annelida, Arthropoda and Mollusca$\newline$ - Mollusca: They have an organ system level of organisation and bilateral symmetry, but they are not segmented.$\newline$ - Therefore, Option 2 does not meet all the criteria.$\newline \bullet$Option 3: Arthropoda, Mollusca and Chordata$\newline$ - As mentioned, Mollusca are not segmented, so this option does not meet all the criteria.$\newline \bullet$Option 4: Annelida, Mollusca and Chordata$\newline$ - Again, Mollusca are not segmented, so this option does not meet all the criteria.$\newline$Therefore, the correct option is Option 1: Annelida, Arthropoda and Chordata.