a$)$ We have the scenario as follows:

cust$($cid$,$ chame, amt$)$ and key is cid, with the following two concurrent transactions.Assume that the individual statements B$1,$ B$2,$ C$1,$ and C$2$ always execute atomically. Bob's amt is $2000$ before either transaction begins execution.$($i$)$ Suppose both transactions T$1$ and T$2$ execute to completion with isolation level Serializable. What are the possible values for Bob's final amt?$(2$ marks$)($ii$)$ Suppose both transactions T$1$ and T$2$ execute to completion with isolation level Read$-$Committed.

What are the possible values for Bob's final amt?

$(2$ marks$)$

$($iii$)$ Suppose transaction T$1$ executes with isolation level Read$-$Committed, transaction T$2$ executes with isolation level Read$-$Uncommitted, and both transactions execute to completion. What are the possible values for Bob's final amt?

$(2$marks$)$