Question of the day: box-sizing: border-box?

What does`box-sizing: border-box` do?

a. Padding and border are included in the element's total width and height

b. Only padding is included in the element's total width and height

c. Only border is included in the element's total width and height

d. Margin, padding, and border are included in the element's total width and height

@"jenny"#p485 I know right. It's quite hard to fully understand as a beginner. The box model in Google Chrome developer tools will help in visualizing it. I used it a lot to fully understand margin and padding. Infact I still use it on some occasions.