What Is the Purpose of the Mashing Step in Beer

What is the purpose of the mashing step in beer making?

A) During mashing, the enzymes of malted barley degrade fermentable sugars, converting them to starches.
B) Mashing increases the surface area available for microbes to adhere to during the fermentation process.
C) Mashing is required to remove residual solids, leaving wort that can be fermented by bacteria.
D) During mashing, the enzymes of malted barley degrade starches, converting them to fermentable sugars.
E) All of the answer choices are correct.