Theories explain phenomena, whilst laws are generalizations which characterize them.
The integumentary system (skin) has been called a membrane and an organ but, it is generally considered a system because it has organs that work together as a system. It is sometimes considered an organ because it contains several types of tissues and a membrane and it covers the body.
It is d because pesticides run off into water, they are absorbed into soil , and they are left in the air , hope this helps :)
