Missing question:
a) mass.
b) diameter.
c) distance from the Sun.
d) density.
Answer is: d) density.
Earth has the highest density of all eight planets in the Solar System, density of the Earth is 5.514 g/cm³.
The four inner planets, closest to the Sun, are all terrestrial planets, which means they are composed of silicate rocks and metals and four outer planets are gas giants, they are composed of hydrogen, helium and water.
Earth is third planet from the Sun.