If the following elements were to combine with each other, choose which demonstrate the law of multiple proportion. select all that apply.

Missing question: Z:X = 7:1 A:Z = 2.5:1 A:Z = 2.2:1 Y:X = 11:1.

Answer is: Z:X = 7:1 and Y:X = 11:1.
Law of multiple proportions or Dalton's Law said that the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. 
In this example ratios are whole numbers, A:Z = 2.5 : 1 and A:Z = 2.2 : 1 are not whole number ratios.

the answer to your question is c

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