CSS question about block elements?

[Crypto6]

I'm really confused and I can't find anywhere in my book that could help me find the answer to this question for my homework:

You have a block element stacked on top of another block element. The upper one has a margin of 30, and the lower one has a margin of 10. How will the browser render them?

A. It will use the value of the element with the smallest margin, effectively placing a margin of 10 pixels between the two elements.

B. It will use the value of the element with the largest margin, effectively placing a margin of 30 pixels between the two elements.

C. It will default to the first element listed, which in this case was 30, effectively placing a margin of 30 pixels between the two elements.

D. It will combine the margins, effectively placing a margin of 40 pixels between the two elements.

Can anyone help me out?

[alhanson]

http://www.w3schools.com/css/css_boxmodel.asp

[dsonesuk]

Clue: Margins of both elements will merge/bleed into each others margin until the larger margin of a element reaches the edge of the other element.