A man ordered a length of rope by telephone from his nearest hardware shop. But when a worker in the shop brought the rope, he found that the man on the telephone had miswritten the order by in-terchanging feet and inches. As a result of this, the length of rope received was only 30% of the length he had ordered. The length of the rope which the man ordered was between `6\ ft\ a n d\ 7 1/2ft` b. `7 1/2ft\ a n d\ 9\ ft` c. `9\ ft\ a b n d\ 10 1/2ft` d. `10 1/2ft\ a n d\ 12\ ft`