Explanation/Reference:
SDO_UTIL.POLYGONTOLINE converts all polygon-type elements in a geometry to line-type elements, and sets the SDO_GTYPE value accordingly. The order of the vertices of each resulting line-type element is the same as in the associated polygon-type element, and the start and end points of each line-type segment are the same point.
If the input geometry is a line, it is returned.
Incorrect Answers:
A: SDO_UTIL.SIMPLIFY simplifies the input geometry, based on a threshold value, using the Douglas- Peucker algorithm.
This function also converts arcs to line stings, eliminates duplicate vertices, and corrects many overlapping edge polygon problems. The reason this function sometimes fixes problems is that it internally calls the SDO_UTIL.RECTIFY_GEOMETRY function at the end of the simplification process to ensure that a valid geometry is returned.
This function is useful when you want a geometry with less fine resolution than the original geometry. For example, if the display resolution cannot show the hundreds or thousands of turns in the course of a river or in a political boundary, better performance might result if the geometry were simplified to show only the major turns.
B: No such command.
E: SDO_GEOM.SDO_MBR returns the minimum bounding rectangle of a geometry object, that is, a single rectangle that minimally encloses the geometry.
References: https://docs.oracle.com/database/121/SPATL/sdo_util-polygontoline.htm#SPATL1241