Most of these people, who wore protective equipment, never tested positive for covid-19 in PCR tests or developed Covid-19 antibodies – proteins that (27) _________ to the outside of viruses, preventing cells from being infected.

Explain:

A. bind (v): bind → bind to something: bind to something (chemically)

B. respond (v): respond → respond to somebody/something: respond to who/what

C. connect (v): connect → connect something to/with something: connect something to something

D. abide (v): obey → abide by something: abide by something

=> Most of these people, who wore protective equipment, never tested positive for covid-19 in PCR tests or developed covid-19 antibodies – proteins that bind to the outside of viruses, preventing cells from being infected. (Most of these people, wear protective equipment, and have never tested positive for Covid-19 by PCR or have developed the Covid-19 antigen – the protein that binds to the outside of the virus, preventing the virus from spreading.) prevent cells from becoming infected.)

→ Choose answer A