What is the formula to calculate the density of the body?

The formula to calculate the density of the body is used to estimate the body fat percentage.
The measurements used to calculate the density of the body are usually taken on the triceps and biceps and on the subscapular and suprailiac folds.
Different equations allow estimating the body density, and known this, the percentage of fat can be calculated using the Brook, Siri or Slaughter equations.
a) Only I is correct.
b) I and II are correct.
c) I, II, and III are correct.