IsoprophI bromide was treated separately with sodium ethoxide under two different conditions.
Reaction I:
Treatment of isopropyI bromide with `(Me_(3)CONa)` at `40^(@)C` gave almost exclusively compound `(A) (C_(3)H_(6))`.
Reaction II:
Treatment of `(i-PrBr)` with `NaOC_(2)H_(5)` at `30^(@)C` yileled compound `(A) (C_(3)H_(6))` along with a small amount of an ether `(B) (C_(5)H_(12)O)`.
Compound `(A)` was readily oxidised by a neutral solution of cold dil. `KMnO_(4)` to give a brown preciptate.
The formations of `(A)` and `(B)` are best explained by:

Options

A. `SN^(2)` reaction and `E2` reaction, respectively
B. `E2` reaction and `SN^(2)` reaction, respectively
C. `E1` reaction and `SN^(1)` reaction, respectively
D. `E2` reaction and `SN^(1)` reaction, respectively

Answer

`b`

Explanation