Which of the following Boolean algebra rules is wrong? A. 0 + A = A B. 1 + A = 1 C. A + A = A D. 1 . x = 1 E. None of the above

The correct answer is: A. 0 + A = A

In Boolean algebra, 0 is the false value and 1 is the true value. Therefore, the rule $0 + A = A$ is wrong because $0 + A$ is always false, regardless of the value of $A$.

The other rules are all correct.

• $1 + A = 1$: This is true because $1$ is always true, so adding it to anything will not change its value.
• $A + A = A$: This is true because $A$ is either true or false, so adding it to itself will not change its value.
• $1 . x = 1$: This is true because $1$ is always true, so multiplying it by anything will not change its value.

Therefore, the only rule that is wrong is $0 + A = A$.