In the object-oriented design of an airline passenger reservation program, suppose that "airplane seat", "aisle seat", and "window seat" have been identified as classes. Focusing specifically on the aisle seat class, how does it relate to the airplane seat class? 1) "aisle seat" exhibits a "has-a" relationship with "airplane seat". 2) "aisle seat" exhibits a "knows-a" relationship with "airplane seat". 3) "aisle seat" exhibits an "is-a-kind-of" relationship with "airplane seat". 4) "aisle seat" and "airplane seat" are independent and unrelated.