The best way to reserve an ad is to:

• A) Create a reservation campaign in AdWords
• B) Contact a Google sales representative
• C) Create a standard video campaign
• D) Enter specifications on the “Reservation” tab

Correct answer is:

• B) Contact a Google sales representative

Explanation:  As an advertiser or ad agency, you can buy placements on a reservation basis-instead of through the AdWords auction–when you want to pay based on the number of impressions (also known as cost-per-thousand impressions) or per day (cost-per-day). Reservation campaigns also let you buy impressions at a fixed rate.

Read more here: https://support.google.com/partners/answer/6030919