下列化學分子式,何者為蛋白質?
\mathrm{C_5H_{10}O_5}
\mathrm{C_{10}H_{16}\ O_{13}N_5P_3}
\mathrm{C_{18}H_{36}O_2}
\mathrm{C_{500}H_{1400}O_{120}N_{75}S_2}