Final answer:
The harshest grievances to the colonists were the ones that infringed on their basic rights and freedoms.
Step-by-step explanation:
The harshest grievances to the colonists were the ones that infringed on their basic rights and freedoms, such as taxation without representation, arbitrary quartering of troops in their homes, and denial of a fair trial. These grievances were seen as direct violations of the colonists' rights as British subjects and fueled their anger and desire for independence. The British laws that required the colonists to house soldiers were particularly offensive and were listed as one of the grievances in the Declaration of Independence.