Answer:
Correct answer is B. All citizens would be equal before the law.
Step-by-step explanation:
A is not correct as Roman laws didn't abolished slavery. Slavery existed until the end of Empire practically.
B is correct as this concept was created back then, but we need to have in mind that many people in Rome weren't considered citizens.
C is not correct as only certain members of society could participate in political life - in Senate for example.
D is totally wrong as gladiator matches were part of everyday entertainment.