Regarding the Size, or Total Megatonnage, of a Hydrogen Bomb

Regarding the size, or total megatonnage, of a hydrogen bomb:

A) It is limited to about 10 megatons by the fact that tritium has a short half- life and thus must react very quickly.
B) It is unlimited, because there is no limit to the amount of fusible material that can be put together.
C) It is unlimited, because there is no limit to the amount of chain- reacting material that can be put together.
D) It is limited, because of the existence of a "critical mass" for fusion, to about one megaton.
E) It is limited, because of the existence of a "critical mass" for fusion, to about 20 kilotons.