question: @ Override public Enumeration < Option > listOptions ( ) { Vector < Option > result = new Vector < Option > ( 1 ) ; result . addElement ( new Option ( "\tThe index of the class attribute. Index starts with 1, 'first'\n" + "\tand 'last' are accepted, '0' unsets the class index.\n" + "\t(default: last)" , "C" , 1 , "-C <num|first|last|0>" ) ) ; result . addAll ( Collections . list ( super . listOptions ( ) ) ) ; return result . elements ( ) ; }
target:  Returns an enumeration describing the available options.