Which one of following reactions will occur on heating $AgNO_3$ above its melting point ?
$(a)\;2AgNO_3 \longrightarrow 2Ag+N_2 +3O_2 \\(b)\;2AgNO_3 \longrightarrow 2Ag_2O+N_2O_3 +O_2 \\(c)\;2AgNO_3 \longrightarrow 2AgNO_2 +O_2 \\ (d)\;2AgNO_3 \longrightarrow 2Ag+2NO_2 +O_2$