Final answer:
An organ system is a group of organs that work together to carry out a particular function vital to a multicellular organism's survival, such as the circulatory system which includes the heart and blood vessels.
Step-by-step explanation:
An organ system is a group of organs that work together to perform a specific function (c). This level of biological organization involves multiple organs that collaborate to execute complex tasks necessary for the survival and proper functioning of multicellular organisms. For example, the circulatory system includes the heart and blood vessels and is responsible for the transport of nutrients, oxygen, and waste products throughout the body.
In most multicellular organisms, specialized cells form tissues, and these tissues combine to create organs. These organs are not isolated entities; they come together to form organ systems. Each organ system has a distinctive role but also works in concert with other systems to maintain the organism's overall health and function. For example, the skeletal system provides structure and protection for internal organs, while also collaborating with the muscular system to facilitate movement.