I am not an expert in COVID-19, but, yes, I think in 2021 everything was uncertain to everyone, including scientists, physicians, and political leaders alike.
So I checked the paper linked. I thought it dealt with questions about face masks, quarantines, and such, but instead there were some silly things like "coronaviruses can spread more quickly through electromagnetic fields".
Nevertheless, to my limited understanding, I think this is questionable because it tends to indicate an absolute answer instead of a probability:
"Coronaviruses can be deadly at any age."
I think this also turned out to be false according to the latest in media, if I recall correctly:
"Coronavirus can be prevented through vaccination."
Someone also linked a paper on these "stimulant substances", but I have no idea about that.
And as said, you have to reflect all this during the uncertainty in the middle of the pandemic in 2021.
I think some of correct answers are definitely wrong.