Explanation/Reference:
Any circular arcs or circles must be densified (using the SDO_GEOM.SDO_ARC_DENSIFY function) or represented as polygons (using the SDO_GEOM.SDO_BUFFER function) before being passed to the TO_GMLGEOMETRY function.
Note: SDO_UTIL.TO_GMLGEOMETRY converts a Spatial geometry object to a geography markup language (GML 2.0) fragment based on the geometry types defined in the Open GIS geometry.xsd schema document.
This function does not convert circles, geometries containing any circular arcs, LRS geometries, or geometries with an SDO_ETYPE value of 0 (type 0 elements); it returns an empty CLOB in these cases.
Incorrect Answers:
A: LRS geometries must be converted to standard geometries (using the
SDO_LRS.CONVERT_TO_STD_GEOM or SDO_LRS.CONVERT_TO_STD_LAYER function) before being passed to the TO_GMLGEOMETRY function.
E: For a polygon with holes, the outer boundary must be stored first in the SDO_ORDINATES definition, followed by coordinates of the inner boundaries.
References: https://docs.oracle.com/cd/B28359_01/appdev.111/b28400/sdo_util.htm#SPATL1249