Is this conclusion drawn from sample or population?

#1
"When asked what they would use if they were marooned on an island with only one choice for a pain reliever, more doctors chose A than B, C or D."
Is this conclusion drawn from population or a sample?
I am confused here because how do we know if on an island there were all the doctors that they could've asked the question?
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"25% of the cars sold in US in 1996 were manufactured in Japan."
Even for this statement how do we know if it was drawn from sample or population?