Explanation/Reference:
SDO_UTIL.RECTIFY_GEOMETRY fixes certain problems with the input geometry, and returns a valid geometry.
This function checks for the following problems that can make a geometry invalid, and fixes the problems in the returned geometry:
Duplicate vertices
Polygon boundary intersecting itself
Incorrect orientation of exterior or interior rings (or both) of a polygon If the input geometry has any other problem that makes it invalid, the function raises an exception.
If the input geometry is valid, the function returns a geometry that is identical to the input geometry.
Incorrect Answers:
B: SDO_MIGRATE.TO_CURRENT upgrades data from the obsolete Spatial relational model (release
8.1.5 or earlier) to the current release, or upgrades one or more object-relational model (release 8.1.6 or later) geometries that need to be upgraded.
C: SDO_GEOM.ALPHA_SHAPE returns the alpha shape geometry of the input geometry, based on a specified radius value.
D: SDO_TUNE.QUALITY_DEGRADATION returns the quality degradation for an index or the average quality degradation for all index tables for an index, or returns the quality degradation for a specified index table. (Deprecated)
E: SDO_CS.TRANSFORM transforms a geometry representation using a coordinate system (specified by SRID or name).
F: SDO_CS.VALIDATE_WKT validates the well-known text (WKT) description associated with a specified SRID.
References: http://docs.oracle.com/cd/E11882_01/appdev.112/e11830/sdo_util.htm#SPATL1243