Two binary numbers are added: 0 b 0 1 plus c 1 1 a gives 1 0 d 1. Then (a, b, c, d) equals

A(0, 0, 1, 1)

B(0, 1, 0, 1) ✓ Correct

C(1, 0, 0, 1)

D(1, 0, 1, 0)

Correct answer: (B) (0, 1, 0, 1)

Explanation

Solving the addition bit by bit from the right gives a equal to 0, b equal to 1, c equal to 0 and d equal to 1.

The units column has 1 plus a ending in 1 with no carry, which forces a to be 0.

The next column has 0 plus 1 plus no carry giving d, so d is 1 with no carry onward.

The third column has b plus 1 ending in 0, which requires b to be 1 and produces a carry.

The leftmost column has 0 plus c plus that carry giving 1, which requires c to be 0.

Reading the four values in order confirms the set 0, 1, 0, 1.

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