Answer:
The British and French evacuated 338,000 troops from Dunkirk.
Explanation:
This massive amount of troops were sitting ducks on the beach and somehow the Royal Navy (along with civilian ships) managed to evacuate all of these troops back to England safely.
The practice which is not sound in conducting individuales is C) conducting in-person interviews and telephone interviews in the same poll.
In-person interviews deliver the most representative results. Telephone surveys provide a good alternative but they need using a larger sample.
