Annotate the following MIPS instructions to indicate source registers and destination registers. A source register is read during the instruction's execution, while a destination register is written during the instruction's execution. a. add $s1, $t2, $t3
b. lw $s3, 8($gp)
c. sw $s4, 12($s5)
d. addi $s1, $zero, 100
e. bne $t1, $t2, else
f. add $s1, $s1, $s1