How can ¹H NMR spectroscopy be utilized to distinguish among 1,2-, 1,3-, and 1,4-phthalonitrile?

The difference in the number of signals in the ¹H NMR spectrum distinguishes the isomers from one another.

The difference in signal heights in the ¹H NMR spectrum distinguishes the isomers from one another.

The difference in the multiplicity of the signals in the ¹H NMR spectrum distinguishes the isomers from one another.

The ¹H NMR spectroscopy cannot distinguish the isomers from one another.