In Figure $5$D of Broman and Woo, they note that they could "fill in the empty cells in the first two columns by repeating the individual, date, and weight values. But it seems wrong to repeat the weights, since they are not repeated measurements."

What element of messy data $($as explained in Wickham$)$ is evident in this aspect of table $5$D$?$

Column headers are values, not variable names

Multiple variables are stored in one column

Variables are stored in both columns and rows

Multiple types in one table

One type in multiple tables