The smallest integer that can be represented by an 8-bit number in 2's complement form is

In an $n$-bit 2's complement representation, the range of representable signed integers is:

For $n = 8$ bits:

• Minimum (smallest) integer: $-2^{8-1} = -2^7 = -128$

• Maximum (largest) integer: $2^{8-1} - 1 = 2^7 - 1 = 127$

The binary representation of $-128$ in 8-bit 2's complement is 10000000.

Hence, the correct option is B.