Load the built-in dataset BOD using:

library(dslabs)
data(BOD)

Do this in RStudio so you can look at the contents of the BOD dataframe

Which of the following is true:

1. BOD is not tidy: it only has six rows.
2. BOD is not tidy: the first column is just an index.
3. BOD is tidy: each row is an observation with two values (time and demand)
4. BOD is tidy: all small datasets are tidy by definition.

Write the number of the correct answer