Symptoms of covid-19, the illness caused ____ the coronavirus, can range from mild to severe. The most common include fever, a dry cough or shortness of breath, but there are other indications you could need to be tested or have a conversation with your doctor.

Not everyone experiences the same symptoms, and the order in which they appear can vary. Some people don’t show any symptoms — what health experts call “asymptomatic” cases — but still could spread the virus to others. Symptoms of a coronavirus infection can emerge anywhere from two to 14 days after exposure to the virus.

A key difference ____ the transmissivity: The coronavirus spreads more easily than the flu. Public health officials have encouraged everyone to get vaccinated against the flu this year ____ help ward off a bad flu season superimposed on a pandemic — and having had a flu shot could also help rule it out if you start to experience any of these symptoms.

Ultimately, infectious-disease doctors say most people won’t be able to tell which illness they have. Common warning signs ____ both include fever, cough, chills and shortness of breath.

The one symptom that’s common with covid-19, but not with the flu, is loss of taste and smell. But not everyone with covid-19 experiences that symptom, and experts warned that someone with allergies or a cold might also struggle to smell because they have a stuffy nose.

Absent a loss of taste or smell, most patients will need a nasal swab to get a proper diagnosis.

(Adapted from https://www.washingtonpost.com/health/2020/12/02/covid-symptoms/)

According to the text, which option is correct?