With current record-setting volumes in air travel, vehicle parking at Calgary lntemational Airport's terminal parkade can reach its maximum capacity during peak periods. The busiest periods are generally Wednesday and Thursday during the week and over long-weekends. When the terminal parkade is crowded. alternate surface parking facilities are made available. ----- of the alternate facilities will result in some additional time or inconvenience
(A) Using (B) Used (C) Use (D) Useful walking to or from the terminal building. Travelers are encouraged to allow additional time during peak periods.
The answer key is (C) Use.
I thought that if you want to start a sentence with a verb, we should use the gerund form, so my choice is (A) Using. Please correct me if I'm wrong.