The hydrogen bonding that created its hexagonal shape....the molecules get closer together and there will be more hydrogen bonding making it solid
note:
Gymnosperms possess several key evolutionary innovations compared to earlier groups such as the clubmosses and ferns. They produce sperm-containing pollen, which is carried through the air by the wind to the female. This innovation has freed these plants from the need for water for sexual reproduction.
Explanation:
Carbohydrates are the main energy source of the human diet.
Fats are also a source of energy but fats are the slowest source of energy.
