Graphic Games, a video game developer, had its latest game "Mega Zombie Kill" banned for sale in lowa to children under the age of $18$ pursuant to a new lowa law restricting the sales of games $-$featuring extreme violence. Graphic Games challenged this action in court on grounds that it was unconstitutional. Which of the following would be the best constitutional theory for Graphic Games to pursue?

First Amendment Free Speech

Fourteenth Amendment Equal Protection

Substantial relationship test

There are no valid constitutional grounds for Graphic Games to challenge this law, because lowa has unrestricted rights to regulate in the interests of the public health, safety and welfare.