Read the passage, then answer the question that follows. Scientists have studied the benefits of hobbies having a pastime reduces stress. It can improve mood, help memory, and strengthen friendships. Relaxing hobbies such as knitting or bird-watching reduce cortisone, the stress hormone. Some hobbies, such as sports and clubs, encourage friendships, and numerous studies have found a connection between relationships and happiness.

Which revision best corrects the underlined sentence?

Scientists have studied the benefits of hobbies. Having a pastime reduces stress.
Scientists have studied the benefits of hobbies, having a pastime reduces stress.
Scientists have studied the benefits of hobbies, but having a pastime reduces stress.
Scientists have studied the benefits of hobbies; however, having a pastime reduces stress.