Question: What is the rem unit based on?

1. The rem unit is relative to the font-size of the p element.
2. You have to set the value for the rem unit by writing a declaration such as rem { font-size: 1 Spx; }
3. The rem unit is relative to the font-size of the containing (parent) element.
4. The rem unit is relative to the font-size of the root element of the page.

Answer: The correct answer of the above question is Option D:The rem unit is relative to the font-size of the root element of the page.