(16 points) Consider the following schedale for four transactions TI, 12.T3 and T TI T2 T3 T4 readA) read(C) read (B) read D) displaytD) read(B) display(B) read D) B:-13+10 write(B) 10 readB) A-A-20 write(A) 12 13 14 i5 16 17 18 19 readkA) A-A+50 write(A) D:-)-30 write(D) read(D) display(B D) C-C+100 21 writetC) 4) Ir we insert sime lock and unkock instructions in the transactions as follows, check if each of TI, T2,T3 and T4 follows the two-phase locking TI T2 T3 T4 lock XC) readiC) lock S(B) read(B) lock S(D) read(D) lock XID) read(D) lock X(A) read(A) A:-A+50 lock S(B) lock S(D) lock S(A) read(A) ock S(B) read(B) display(B) upgrade( A) unlock(B) A A-20 write(A) unlock(A). or read(B) read(D) display(D) unlock(D) upgrade(B) B:-B+10 write(B) unlock(B) write(A) display(B+D) C-C+100 write(C) unlock(C) unlock(D) unlock(B) unlock(A) D-D-30 write(D) unlock(D)