Kabuki became a part of Japanese national culture primarily through the widespread performance and accessibility of the art form. While all the options you provided have some aspect of truth in relation to kabuki's development, the most accurate reason for its integration into national culture is:
Groups traveled around the country performing kabuki.
This allowed kabuki to reach diverse audiences across Japan, not just the elite. As performance troupes traveled, they spread the art form’s popularity, influences, and styles throughout the nation. Over time, kabuki evolved and adapted, becoming a significant cultural symbol and an accessible entertainment medium for people from various social classes.
Additionally, while kabuki did gain prestige and was appreciated by the imperial court and aristocracy, it also thrived in the common populace, which helped to solidify its place within the broader Japanese cultural identity.