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A relay logic diagram and its PLC ladder diagram are shown below. PB1 LS1 SOL1 1/4 1/6 0/0 PB2 CR3 1/7 B/0 1/8 CR3 LS4 M1 B/0 1/9 0/1 In order to energise the control relay CR3: O The limit switch LS2 and push button PB2, and the limit switch LS3 must be closed. O The limit switch LS2 or the push button PB2, or the limit switch LS3 must be closed. O The limit switch LS2 or push button PB2, and the limit switch LS3 must be closed. O The limit switch LS2 and push button PB2, or the limit switch LS3 must be closed. O The limit switch LS2 and push button PB2, and the push button PB1 must be closed. LS2 LS3 1/5