Hi there!
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Question 15:</h3>
We can see from the graph the spikes during the dry years in beak size, which happen every single time there is a dry year. We can then reasonably infer that this would happen with an extended period of drought, however more significantly as well.
This makes your answer B, the birds with larger beaks would be more numerous.
Looking through the other answer choices - A is incorrect, as just stated above the larger ones would likely become more numerous. C is also incorrect, as we can see from the graph during dry years it does influence ground finches. Finally, D is also incorrect, as we can see the average obviously moving upwards to those with bigger beaks.
<h3>Question 16:</h3>
We are given that during dry years, the finches eat larger seeds as the smaller seeds are less abundant. This means that those finches with larger beaks would have an advantage for survival, as it is easier for them to eat these larger seeds compared to those with smaller beaks. This then means that more and more finches with larger beaks would survive, making the overall population have larger beaks over time.
This makes your answer C, different adaptations gave some birds a better chance for survival.
Looking through the other answer choices - A is incorrect, as they cannot just decide to acquire larger beaks. B is incorrect, as mutations do not just happen and cause such a big shift, and in an efficient direction (most mutations end up not affecting the animal at all. Finally, D is incorrect, as I don't think beaks have the capability of getting larger as they are exercised more.
Hope this helps! Feel free to let me know if you have any additional questions about this specific problem.
