If ab=ab, then ba is called

Since, $\frac{a}{b} = \frac{a}{b} \Rightarrow \frac{a}{b} = \frac{a}{b} \times 1 \Rightarrow \frac{a}{b} \times \frac{b}{a} = 1$

$\frac{b}{a}$ is called the multiplication inverse of $\frac{a}{b}$ . Hence $\frac{a}{b} \times \frac{b}{a} = 1$

So $\frac{b}{a}$ is not additive inverse of $\frac{a}{b}$ and also

$\frac{a}{b} = \frac{a}{b} \Rightarrow \frac{a}{b} + (\frac{- a}{b}) = 0$

So , $\frac{- a}{b}$ is additive inverse of $\frac{a}{b}$

But here asked about $\frac{b}{a}$

B: Since $\frac{a}{b} \times \frac{b}{a} = 1$ . Clearly says that $\frac{b}{a}$ is multiplicative inverse of $\frac{a}{b}$

If $\frac{a}{b} = \frac{a}{b}$ , then $\frac{b}{a}$ is called