[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]
Let's balance the given equation ~
[tex]\qquad \sf \dashrightarrow \:S_8 + O_2 \rightarrow SO_3[/tex]
[tex] \textsf{Step 1 - balance Sulphur (S) on both sides} [/tex]
[tex] \textsf{[ By multiplying} [/tex] [tex] \sf{SO_3} [/tex] [tex] \textsf{by 8 on product side ]} [/tex]
[tex]\qquad \sf \dashrightarrow \:S_8 + O_2 \rightarrow 8 \: SO_3[/tex]
[tex] \textsf{Step 2 - balance Oxygen (O) on both sides} [/tex]
[tex] \textsf{[ By multiplying} [/tex] [tex] \sf{O_2} [/tex] [tex] \textsf{by 12 on reactant side ]} [/tex]
[tex]\qquad \sf \dashrightarrow \:S_8 +12 \: O_2 \rightarrow 8 \: SO_3[/tex]
So, we can infer that the Correct choice is D
