The sentence that contains an adverb clause is A. If you visit Pennsylvania, take the self-guided, covered-bridge tour.
The other sentences are simple, which means they have only independent clauses, and no dependent ones such as an adverb clause.
Answer:
Electricity is one of the most important blessings that science has given to mankind. It has also become a part of modern life and one cannot think of a world without it. ... It is used for lighting rooms, working fans and domestic appliances like using electric stoves, A/C and more. All these provide comfort to people.
Explanation: