Which of these fields is used to classify organisms?

Which strategy is an example of how companies may upgrade themselves to meet changing customer preferences? a.doing door-to-door sellingb.using billboards to advertise the productsc. making online shopping services availabled.giving discounts on products

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Where does the esophagus lead to in a frog?