Hi, just doing the second quiz in CSS grid course and this came up…

Can someone help me understand the answer? As far as I can see, if there are 2 rows and 2 columns, that makes 4 grid cells that are all occupied by the 4 boxes, so there won’t be any explicit cells to fill and the fifth box will be implicit and so 70px wide. What am I missing?

Many thanks, Bils