Choice Dhoice A is the correct answer. This demonstrates the additive identity property in reverse.

1. Start with the equation: $x + 0 = 42$
2. Recognize the identity: Adding zero to any number doesn't change it
3. Conclude: $x = 42$
4. Verify: $42 + 0 = 42$ ✓

Since adding zero changes nothing, $x$ must already be 42.

💡 Additive Identity: For any number $a$, we have $a + 0 = a$. So if $x + 0 = 42$, then $x = 42$.

You could also solve this algebraically by subtracting 0 from both sides: $x = 42 - 0 = 42$.

Choice Dhoice B is incorrect because zero is what's being added, not the value of $x$. Don't confuse the addend with the sum.

Choice Dhoice C is incorrect because this is the negative of the correct answer. There's no reason to introduce a negative sign here.

Choice Dhoice D is incorrect because 1 has no relevance to this problem. This might result from confusing additive identity (0) with multiplicative identity (1).