The number 43 in 8-bit 2's complement representation is:

For a positive number, the 2's complement representation is the same as its ordinary binary representation, with the sign bit 0.

43 = 32 + 8 + 2 + 1.

So the binary bits are:
32 16 8 4 2 1 -> 1 0 1 0 1 1, i.e. 101011.

In 8-bit form, add two leading zeros: 00101011. Hence the correct representation is 00101011.