English to Spanish Other Sports / Fitness / Recreation Archery

When hunting with a bow during the archery only season, you should:
a.
keep your firearm unloaded until you need it.
b.
keep your firearm loaded in case you need it.
c.
keep your firearm in your backpack.
d.
never carry a firearm while hunting.

Can anybody clarify what "only" means in this context and how should it be translated? Thank you!!