To improve the connection between the two underlined sentences and indicate that the upcoming information builds upon what has already been presented, the best choice would be B. In addition.
Revised excerpt: "Though Ms. Jasmine does not personally attest to the causes of this organization, the banner is not violating her rights. In addition, Ms. Jasmine is free to apply for permission to hang a separate banner in support of her beliefs or to express her beliefs verbally."