Which of the following pairs of compounds cannot demonstrate the law of multiple proportions?

The percentage of copper and oxygen in samples of $CuO$ obtained by different methods were found to be the same. This illustrates the law of

Carbon and oxygen form two known compounds. One compound contains $42.9\%$ carbon,while the other contains $27.3\%$ carbon. This illustrates the law of:

$A$ box contains some identical red-coloured balls,labelled as $A$,each weighing $2 \ g$. Another box contains identical blue-coloured balls,labelled as $B$,each weighing $5 \ g$. Consider the combinations $AB, AB_2, A_2B$ and $A_2B_3$ and show that the law of multiple proportions is applicable.

Explain the Law of Multiple Proportions.

Which of the following examples illustrates the Law of Multiple Proportions?