A subclass/superclass relationship is modeled with: A line that leads to a circle with a D,O, or U in it, with a continuation of the line with a arrow and a rectangle. A line that possibly leads to a circle with a D or O in it, with a contincation of the line with a arrow and a rectangle. A line that leads to a circle with a D or O in it, with a continuation of the line with a arrow and a rectangle. A line that possible leads to a circle with a D,O, or U in it, with a continuation of the line with a arrow and a rectangle