It's tricky to say definitively which body system is the "largest" because it depends on how you define "largest."

Here's a breakdown:

* By weight: The integumentary system (skin) is the largest organ system by weight, making up about 15% of an adult's body weight.

* By surface area: The integumentary system (skin) also wins in terms of surface area.

* By complexity: The nervous system is incredibly complex, with billions of neurons interconnected in intricate networks.

So, the answer depends on your definition of "largest." The integumentary system (skin) wins in terms of weight and surface area, while the nervous system is arguably the most complex.