Which of the gases contain the same number of molecules as that of $16\; g$ oxygen ?

Question

$$\begin {array} {1 1} (a)\;16\;g\;of\;O_3 & \quad  (b)\;32\;g \;of\;SO_2 \\  (c)\;16\;g\;of\;SO_2 & \quad (d)\;All\;of\;the\;above \end {array}$$