Consider two transactions T$1$ and T$2,$ which pair$($s$)$ of operations is in conflict? i$.$ T$1$ Read$($X$),$ T$2$ Write$($Y$)$ ii$.$ T$1$ Write$($Y$),$ T$2$ Write$($Y$)$ iii. T$1$ Read$($X$),$ T$2$ Read$($X$)$ iv$.$ T$1$ Write$($Z$),$ T$2$ Read$($Z$)$