Step 1: Recall how groups affect the ring.
In electrophilic substitution, a group that pushes electron density into the benzene ring makes it react faster (activating), while a group that pulls density away makes it react slower (deactivating).
Step 2: Look at the amide-type group.
In $-NHCOCH_3$ the nitrogen lone pair is tied up by the neighbouring carbonyl, so it is less free to feed the ring. This makes the group deactivating overall compared with a plain amino group.
Step 3: Look at the ester-type group.
In $-OCOCH_3$ the oxygen lone pair is also drawn toward the carbonyl, so it gives less to the ring and acts as a deactivating group. So Statement I, which calls both deactivating, is correct.
Step 4: Look at the hydroxyl group.
$-OH$ has lone pairs on oxygen that strongly push into the ring, making it a strong activator.
Step 5: Look at the ethyl group.
$-CH_2CH_3$ is an alkyl group that donates electron density by induction and hyperconjugation, so it is a mild activator. So Statement II, which calls both activating, is correct.
Step 6: Combine.
Both statements are correct.
\[ \boxed{\text{Both statements I and II are correct}} \]