There are 5 blades, equally spaced. So the angle between adjacent blades is 360° / 5 = 72°. So you can rotate the fan 72° and the blades will align again.
<h2>B</h2><h2>C</h2><h2>E</h2><h2></h2><h3>are the correct answers!</h3><h3></h3><h3></h3><h3></h3><h3></h3><h3></h3><h3><em>Let me know if I'm wrong!</em></h3>