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'.
Q: Question: The nitrogen:
Options: <1> It is a highly reactive gas at room temperature. <2> Nitrogen molecules are constituted by two atoms linked together by a single bond. <3> It has a higher reactivity than other isoelectronic molecules such as CO, CNo or NO +. <4> At a sufficient temperature, it reacts with H2 to give NH3. <5> It barely forms binary compounds with the rest of the elements of the Periodic Table.
A:
4