Under which circumstances would protesters’ right to assembly most likely be protected? if protesters were picketing on an alleged criminal’s front lawn if protesters were marching on the statehouse in favor of marriage for all if protesters were inciting others to destroy restaurants serving unhealthy foods if protesters were throwing rocks at police to prevent arrest

If protesters were marching to the statehouse in favor of marriage is the right option where right to assemble is most likely be protected as all other options attempt to indulge in violence in one way or the other which is against the law. Everybody has the right to assemble peacefully and without arms and non-violently.  

The correct alternative is B. "If protesters were marching on the statehouse in favor of marriage for all".

Everybody has the right to protest peacefully and without arms. In the situation brought up by alternative B, it seems to be a peaceful protest, and for this reason, there is no reason for their rights not to be protected.

On the other hand, the other alternatives entice some sort of violence: picketing, destroying restaurants, throwing rocks. Those examples are not peaceful, and therefore, their right to protest wouldn't be protected.