The answer is B. Team : Competition.
A bunch of keys is a group of keys that are typically held together by a ring or chain. A team is a group of people who work together to achieve a common goal. A competition is an event in which people or teams compete against each other to win a prize.
In each pair, the first item is a collection of the second item. A bunch of keys is a collection of keys, a team is a collection of people, and a competition is a collection of people or teams.
A hound is a type of dog, a beehive is a home for bees, and a bouquet is a collection of flowers. These items are not collections of each other.