$12.$Let R$1=\{(1,2),(2,3),(3,4)\}$ and R$2=\{(1,1),(1,2),(2,1),(2,2),(2,3),(3,1),(3,2),(3,3),(3,4)\}$ be relations from$\{1,2,3\}$to$\{1,2,3,4\}.$ Find a$)$R$1$ R$2$ b$)$R$1$ R$2$ c$)$R$2$ R$1$