Final answer:
The grievance in the Declaration of Independence that the king has refused his assent to necessary laws emphasizes the importance of protecting individual rights, which aligns with the founding principle of unalienable rights.
Step-by-step explanation:
The grievance quoted from the Declaration of Independence, "He has refused his Assent to Laws, the most wholesome and necessary for the public good," is directly related to the founding principle of unalienable rights. The denial of these important laws by the king contradicted the idea that governments should secure the rights of the people, which include life, liberty, and the pursuit of happiness. Therefore, the correct answer to how this grievance relates to the founding principle of unalienable rights is: a. It emphasizes the importance of protecting individual rights.