A．They have reduced the prices of their cars.
B．They have laid off plenty of short-term contract workers.
C．They have laid off many full-time salaried employees.
D．They have narrowed down their foreign market.

A．Major changes in the migration routes of hummingbirds.
B．The adaptation of hummingbirds to urban environments.
C．Concern about the reduction of hummingbird habitats.
D．The impact of ecotourism hummingbird populations.

A．An increase in the ecotourism industry.
B．An increase in the use of land to raise crops and cattle.
C．A decrease in relative studies about their protection.
D．A decrease in the distance traveled during migration.