The correct option is B organ
An organ consists of tissues, organised in a specific proportion and pattern to perform specialized functions. Eg: Lungs, stomach, kidneys, etc.
Two or more organs that perform a common function by their physical and/or chemical interaction, form an organ system such as the digestive system and respiratory system.
Multiple organ systems that coordinate with each other for the survival of an individual form an organism. This is known as the division of labour.
Cellular system is a distractor.