For the conversion of this C code to assembly, could someone explain in detail why for the MIPS code we shift $s3 by 2 bits please?

Example Convert to assembly: Loop: sll $11, $s3, 2 add $11, $11, $s6 while (save[i] k) $t0, 0($t1) bne $t0, $s5, Exit addi $s3, $s3, 1 Loop i and k are in $s3 and $s5 and base of array save0 is in $s6 Exit