Something experimental is something that is an operation or procedure carried out under certain conditions in order to discover something unknown or to test or establish a hypothesis. Characters engaging the audience was not so innovative, nor is having creative characters. Nothing special about portraying characters how they are in real life. The answer that fits best the idea of experimental is:
3.The characters are presented in new or unusual ways.
The first one is the correct way to use it, since it separates the parts of the sentence into fragments that can still be understood without changing the meaning of the entire sentence.
