Read the passage below, and identify its two central ideas. Then explain how each central idea is backed up by supporting details.
Passage
Having a pet is a great way to reduce stress, but the decision to care for a pet should not be taken lightly. Studies show that the simple act of petting an animal can decrease levels of stress-producing hormones in the body, which can help to lower blood pressure. Pet ownership also has psychological benefits, such as enhancing feelings of safety, independence, and control, which lead to a greater sense of relaxation. Pets make wonderful companions, but it's also important that owners ensure they have the ability to take care of their animals properly. Pets are often unable to care for themselves and must rely on their owners for food, shelter, and exercise. Owners should consider if they can properly provide a pet with these necessary things before bringing one home. Pets can be both a great joy and a big responsibility.