C-02-Q123mediumsingle_mcqFor R={(2,1),(2,2),(2,3)}R = \{(2, 1), (2, 2), (2, 3)\}R={(2,1),(2,2),(2,3)}, DomR=\operatorname{Dom} R =DomR=a{2}\{2\}{2}b{1,2,3}\{1, 2, 3\}{1,2,3}c{1,2}\{1, 2\}