Many Cool Season Plants do not grow well during hot weather. When it get hot the plant closes the stomata in order to save water. With the stomata closed the plant
cannot make any sugar which will cause the plant to stress and suffer damage or
eventual death. This process is called:

b brown mice / white sand dunes

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.

i believe it's c. the trait for large beaks will be passed on to future generations through natural selection.

since eventually smaller beaks would have to find another source of food or even eventually just die out from the lack of food.