Question

Which sentence contains an adjective clause?
Our weekly meeting was almost canceled because a snowstorm was forecasted.
When the sun came out, we decided to go ahead with the meeting.
Pedro, who has been all over the world, gave a thorough presentation on travel safety.

Answer 1

The only sentence which contains an adjective clause is the last one - Pedro, who has been all over the world, gave a thorough presentation on travel safety. 
The other options contain only adverb clauses - because a snowstorm was forecasted and when the sun came out.