Read the following sentences and find out what kind of adverb the underlined ones are.
Mark is too shy to go in front of a crowd.

The correct answer is: Adverb of degree

Solution : Option(b) Adverb of Degree.
An Adverb of Degree is used to discuss the degree or intensity of an adjective , an action , or another adverb. Example - much , more, too, extremely etc.
Here, in statement  "Mark is too shy to go in front of the crowd" , the word "too" tells the intensity of the adjective "shy". So, Adverb of degree.