A、By taking a handgun. B、By hiring a bodyguard. C、By bringing large dogs. D、By disguising himself as others. C短文指出。为了防止被抢，讲话者在出诊

House calls are making a small comeback, as hospitals discover they can provide better treatment for a lower cost by sending teams of doctors, nurses and others to patients’ homes after they have been discharged. There was a time when house calls were a common way to deliver medical care— especially in low-income neighborhoods of major cities. Few of us are still around who practiced medicine this way, but it wasn’t uncommon from the 1950s through the 1980s, when medical residents earned anywhere from zero to ＄300 per month, to supplement our incomes this way. In the Bronx, where I worked, doctors would sign their patients out to us or the medical society, and we would be on call until the next morning. We charged ＄7 before midnight and ＄10 after—cash only. We carried drugs in our medical bags, and robbers knew it, so the threat of being robbed for drugs or cash was very real. Some of us, myself included, brought large dogs on some calls. Patients loved this system. Instead of sitting in an emergency room for hours, they usually received prompt attention at a lower cost. We’d arrive to a complaint of chest pain or a child with a fever, and do a thorough examination and dispense medication on the spot. Anxiety attacks were another common problem. I’d get a call from someone saying her husband was having a heart attack. “Where is he now?” I’d ask. “He’s outside getting some air,” she would respond. Heart attack patients can’t do that, so I knew there was no emergency. But when I got there, I sometimes dispensed a sedative.
16. What does the speaker say about the house calls between the 1950s and 1980s?
17. How did the speaker prevent himself from being robbed?
18. Why did patients love house calls?
19. What was the common problem for the speaker?