Inhalation is the active movement of air into the lungs. When the diaphragm contracts, it moves downward, and the intercostal muscles contract to lift the ribs, expanding the chest cavity. This larger volume lowers the pressure inside the lungs below atmospheric pressure, so air flows in through the airways until pressures balance. Exhalation, in contrast, is typically passive at rest and involves air leaving the lungs as the chest recoils. The other options don’t relate to the act of bringing air in.

Blood pressure describes the force of blood against the walls of the arteries as the heart pumps. This pressure changes with each heartbeat, with systolic pressure being the force during contraction and diastolic pressure during relaxation. It’s commonly written as a ratio like 120/80 mmHg. A blood pressure monitor is the device used to measure this force, not the force itself. The other options don’t refer to the force exerted by blood on vessel walls.

The idea behind this question is how airway adjuncts help keep the airway open. A nasopharyngeal airway is a flexible tube that is inserted through the nose and extends back to the pharynx to hold the airway open. Its flexible design allows it to follow the natural contours of the nasal passages and reach behind the tongue, helping prevent airway obstruction without triggering a strong gag reflex in many patients. This makes it useful for people who are semi-conscious or unable to maintain their airway on their own, while still allowing them to breathe more comfortably. In contrast, an oropharyngeal airway is a rigid device placed through the mouth into the oropharynx to keep the tongue from occluding the airway; it can provoke coughing or gagging and isn’t ideal for patients with a responsive gag reflex. Suctioning is a procedure to remove secretions, not an airway device, and artificial ventilation refers to providing breaths directly rather than acting as a spacer to keep the airway open.

The ilium is responsible for the superior and widest portion of the pelvis. It’s the largest of the hip bones and has a broad, wing-like blade that rises to form the upper boundary of the pelvic cavity. The iliac crests mark this top edge, contributing to the wide opening of the pelvis. The other bones—ischium forms the lower posterior part, pubis forms the anterior portion, and the sacrum sits behind as part of the pelvic ring but does not define the widest, superior area. So, the ilium best explains why the top of the pelvis is broadest.

The part of the peripheral nervous system that governs involuntary motor functions is the autonomic nervous system. It controls automatic activities like heart rate, digestion, respiratory rate, pupillary changes, and glandular secretion, keeping the body in balance without conscious effort. It operates through two main branches: the sympathetic system, which prepares the body for action, and the parasympathetic system, which promotes rest and digestion. The other terms don’t describe a nervous-system division: an arteriole is a blood vessel, automaticity refers to spontaneous impulse generation, and the calcaneus is a heel bone.