(a) The fact that a person who allegedly violated Section 25100 attended a firearm safety training course prior to the purchase of the firearm that was obtained by a child in violation of Section 25100 shall be considered a mitigating factor by a district attorney when deciding whether to prosecute the alleged violation.
(b) In any action or trial commenced under Section 25100, the fact that the person who allegedly violated Section 25100 attended a firearm safety training course prior to the purchase of the firearm that was obtained by a child in violation of Section 25100 is admissible.