can someone explain what the3 link register is doing I do not understand how 08000118 lr is associated with progam counter is 08000120

When PC is 0x08000100 in the following assembly program, the stack pointer (SP) is 0x20002000 Show the value of link register (LR) and the whole stack content when PC 0x08000120 Memory Address 0x08000100 0x08000104 0x08000108 0x08000100 0x08000110 0x08000114 0x08000118 0x08000110 0x08000120 0x08000124 0x08000128 0x08000120 0x08000130 0x08000134 0x08000138 Instruction MOV R0,#2 BL QUAD B ENDL SQ1 PUSH LR) MUL RO, RO BL SQ2 POP P SQ2 PUSH LR) Stack MUL Re, RO POP (PC) QUAD PUSH LR) BL S01 POP TLR BX LR 0x20002000 0x20001FFC 0x08000130 0x20001FF8 ex08000118 0x20001FF4 1 ENDL When PC is 0x08000100 in the following assembly program, the stack pointer (SP) is 0x20002000 Show the value of link register (LR) and the whole stack content when PC 0x08000120 Memory Address 0x08000100 0x08000104 0x08000108 0x08000100 0x08000110 0x08000114 0x08000118 0x08000110 0x08000120 0x08000124 0x08000128 0x08000120 0x08000130 0x08000134 0x08000138 Instruction MOV R0,#2 BL QUAD B ENDL SQ1 PUSH LR) MUL RO, RO BL SQ2 POP P SQ2 PUSH LR) Stack MUL Re, RO POP (PC) QUAD PUSH LR) BL S01 POP TLR BX LR 0x20002000 0x20001FFC 0x08000130 0x20001FF8 ex08000118 0x20001FF4 1 ENDL