INSTRUCTION: Read the following text to answer the question.

Around a billion people still smoke, so we clearly have more to learn about effective treatments for nicotine addiction. Medications that can help include bupropion, a classical antidepressant, which mostly helps people who are depressed to stop smoking; and varenicline, which imitates nicotine in some ways but prevents nicotinic receptors from being fully activated.

Some nicotine cessation products, such as gums and patches and inhalers, use nicotine itself in the hope that it can be delivered in small enough quantities and over a long enough period of time that nicotine receptors will only be partially chaperoned, helping to reduce upregulation while the individual works on quitting smoking.

We still need more and better science to figure out the pharmacokinetics of nicotine: How fast does it enter the body? How long does it stay in the body? To that end, along with a team of collaborators — including Caltech professors Wei Gao (professor of medical engineering), Dennis Dougherty (George Grant Hoag Professor of Chemistry), and Stephen Mayo (Bren Professor of Biology and Chemistry), and Professor Neal Benowitz of UC San Francisco — we have been working to develop a wearable device that resembles the continuous glucose monitor used by Type 1 diabetes patients.

We will use this monitor to measure nicotine while a person smokes or vapes or uses a nicotine pouch so that we can fully understand how an individual metabolizes nicotine and relate this knowledge to a century’s worth of work on nicotinic receptors and nicotine addiction.