Answer:
The correct answer would be, Brainstorming.
Step-by-step explanation:
Dean used a technique, called Brainstorming.
Brainstorming is a process of generating new and innovative ideas by group discussion.
When a group of people discuss anything and generate ideas or give innovative solutions of the problem being discussed, they are actually resolving the problem and this process is called as brainstorming.
So in this question, when Dean went to his team to seek solution to the problem which he recently encountered, his team came up with surprisingly new innovative ideas that astonished Dean. So Dean actually used a technique called Brainstorming to make his team generate solution for the problem with their ideas and suggestions.