Insulin is a protein hormone. how would insulin bind to its target cells? through a receptor on the cell membrane that transduces its signal to the cell's dna through a receptor on the cell's nucleus that transduces its signal to the cell's dna by binding to a receptor in the cytoplasm that binds to the cell's dna by binding to the cell's dna directly, after passing through the cell membrane

An insulin receptor (i.e. the receptor which insulin binds to) is a cell-surface receptor (i.e. the receptor is embedded in the cell-surface membrane). 

Thus, the second, third, and fourth options are incorrect, as insulin does not bind to receptors on the cell's nucleus, nor in the cytoplasm, nor the DNA directly. 

Option one is correct, as the signal is a multistep process, where insulin has to first activate the molecules on the insulin receptor, which will then activate other molecules, and transfer the signal down a signalling pathway. 

Hope this helps! :)