The question asks for the additive inverse of $\frac{3}{8}$. The additive inverse of a number $x$ is the number that, when added to $x$, equals zero. For any fraction $\frac{a}{b}$, its additive inverse is $-\frac{a}{b}$.

Given: $\text{The additive inverse of } \frac{3}{8} \text{ is } -\frac{3}{8}.$

Now, let's look at the provided options in the image:

1. $-\frac{3}{8}$ (This is the correct answer)
2. $\frac{8}{3}$ (Incorrect; this is the reciprocal, not the additive inverse)
3. $8/3$ (Same as option 2, incorrect)

Thus, the correct answer is the first option: $-\frac{3}{8}$.

Would you like further details or have any questions?

Here are some related questions:

1. What is the additive inverse of a negative fraction?
2. How do you find the multiplicative inverse of a fraction?
3. What is the difference between an additive inverse and a multiplicative inverse?
4. Can the additive inverse of zero be defined?
5. How would you add two fractions with different denominators?

Tip: The additive inverse of a positive number is simply its negative counterpart, and vice versa.