Some individuals of a particular species of sea bird underwent a genetic mutation that resulted in larger beaks. The larger size
of beaks helped these birds to break open clams and other mollusks for food. It also helped them defend themselves against predators. After many generations, almost all of the birds in the population had big beaks. For which two reasons did this phenomenon occur?
Its natural selection and survival of the fittest.
Explanation:
Variations occur due to sudden mutations. Some mutations might be harmful but some mutations may add advantageous feature to the species. Since large beaks helped those birds to break open clams, they survived better than the others. During the struggle for existence the one with better train survives and forms the future generations. This is called survival of the fittest. The one which is fit gets selected by the nature, a concept of natural selection proposed by Darwin.
I don't know the options but my best guess would be erosion. Every time water comes on the beach is takes sand which erodes the beach. Hope that helps!
