The correct answer is option 3, Cook Strait. Cook Strait is a body of water that separates the North Island and the South Island of New Zealand. It is named after the British explorer Captain James Cook, who was the first European to explore and chart the area in 1770.

Option 1, Foveaux Strait, is not correct. Foveaux Strait is a body of water located between the South Island and Stewart Island/Rakiura, which is located south of the South Island.

Option 2, Bass Strait, is also not correct. Bass Strait is a body of water located between the Australian mainland and the island of Tasmania.

Option 4, Torres Strait, is also not correct. Torres Strait is a body of water located between Australia and Papua New Guinea.

Therefore, the correct answer is Cook Strait, as it separates the North and South Islands of New Zealand.