The Montreal Protocol limited the world’s use of chemicals like Chlorofluorocarbons (CFCs). Which sentence best indicates that the Montreal Protocol led to improvements in the thickness of the ozone layer? When ozone was first measured by satellite in 1979, the average concentration above Antarctica was 225 Dobson units (DU). In 1989, when the Montreal Protocol took effect, it was 127 DU. The lowest level was 92 DU in 1994.By 2019, the value was back up to 167 DU. Excerpt courtesy of NASA

the scientific method.

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.