$15.$ In real mode, MOV AX$,$BX is using$($a$)$ register $($b$)$direct$($c$)$ immediate $($d$)$indirectaddress mode:$16.$ In real mode, MOV AX$,$ ITEM is usingaddress mode:$($a$)$ register $($b$)$direct$($c$)$immediate$($d$)$indirect$17.$ In real mode, MOV AX$,1234$H is using$($a$)$ register $($b direct $($c$)$immediate$($d$)$ indirect$18.$ In real mode, MOV AX$,$ LBX$]$ is using$($a$)$ register$($b$)$ direct$($c$)$ immediate$($d$)$ indirectaddress mode:$-$ address mode:$19.$ Which of the following instructions is not valid?$($a$)$ PUSH AH$($b$)$ PUSH AX$($c$)$ PUSH BX$($d$)$ PUSH CS$20.$ Which segment is not included in assembly program?$($a$)$code segment$($b$)$data segment$($c$)$stack segmentd$)$ directive segment