Identify phrases and clauses from the given options and categorize them.

Here's the categorization of the given word groups into clauses and phrases:

Clauses:
A clause contains both a subject and a finite verb.

• whose class is extremely difficult
  • Subject: "class" (modified by "whose")
  • Verb: "is"
• unless you are afraid
  • Subject: "you"
  • Verb: "are"
• provided that she answers
  • Subject: "she"
  • Verb: "answers"

Phrases:
A phrase is a group of words that does not contain both a subject and a finite verb.

• might have gone caving
  • No subject. "Might have gone" is a verb phrase, but it lacks a subject within this group.
• the desperately exhausted man
  • No subject and no finite verb. This is a noun phrase.

Here is the sorted list:

Clauses

• whose class is extremely difficult
• unless you are afraid
• provided that she answers

Phrases

• might have gone caving
• the desperately exhausted man