Give the stereochemical structures of `B and C.
` 2,overset("Erythro-")underset((A))(3-"dibromobut ane") overset ("Nal/Acetone") rarr (B)overset("Cold alk")underset (KMnO_(4))rarr(C)`

Explanation

To solve the question regarding the stereochemical structures of compounds B and C derived from erythro-2,3-dibromobutane (compound A), we will follow these steps:

### Step 1: Draw the structure of compound A (erythro-2,3-dibromobutane)
- Erythro-2,3-dibromobutane has two bromine atoms on the second and third carbon atoms, and since it is erythro, the bromine atoms are on the same side of the carbon chain.
- The structure can be represented as follows:

```
Br Br
...