Instructions: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: Pyruvate dehydrogenase (PDH):
Options: <1> It catalyzes the reversible transformation of pyruvate into acetyl-CoA and vice versa. <2> It catalyzes the irreversible carboxylation of pyruvate into citrate, and with it, its entry into the citric acid cycle. <3> It connects the degradation of carbohydrates, with the synthesis of acetyl-CoA and its entry into the citric acid cycle. <4> It allows the use of acetyl-CoA derived from the degradation of fatty acids for the synthesis of glucose. <5> It is activated in the presence of high concentrations of acetyl-CoA and NADH + H +.
Output:
3