The correct answer is: A new slide is inserted between the first and second slide.
When you select the first and second slide and then click on the New Slide button on the toolbar, a new slide is inserted between the two selected slides. The new slide will have the same layout as the previous slide.
Option A is incorrect because the new slide is inserted between the first and second slide, not as the first slide.
Option B is incorrect because the new slide is inserted between the first and second slide, not as the second slide.
Option C is incorrect because the new slide is inserted between the first and second slide, not as the third slide.
Option D is incorrect because a new slide is inserted between the first and second slide.