This group was made up of fierce fighters who would protect Georgia's southern border from invasion by the Spanish.

a. Highland Scots
b. Malcontents
c. Salzburger
d. Trustees

a. Highland Scots

a. Highland Scots

To determine which group was made up of fierce fighters who would protect Georgia's southern border from invasion by the Spanish, we need to analyze the characteristics and roles of each group.

a. Highland Scots: The Highland Scots were a group of Scottish immigrants who settled in Georgia. While they were known for their ruggedness and resilience, they were not specifically organized or tasked with protecting Georgia's southern border from Spanish invasion.

b. Malcontents: The Malcontents were a group of colonists who were discontent with the rules and regulations imposed by the Trustees of Georgia. Their grievances were primarily related to land ownership and limitations on trade. While they may have been strong in their opposition to the Trustees, they were not primarily focused on protecting the border from Spanish invasion.

c. Salzburgers: The Salzburgers were a group of Protestant refugees from Austria who settled in Georgia. They were known for their strong religious beliefs and were dedicated to creating a godly community. However, their main objectives were religious freedom and establishing a successful agricultural colony, rather than military defense.

d. Trustees: The Trustees were a group of individuals who were granted control over the Georgia colony by King George II. While they were responsible for governance and the overall development of the colony, they did not have a specific military role or a group of fighters dedicated to protecting the southern border.

Based on these descriptions, the group that was specifically focused on protecting Georgia's southern border from Spanish invasion would be:

a. Highland Scots - Although the Highland Scots were not specifically organized for this purpose, they were known for their fierce fighting skills and could potentially be seen as a group capable of defending Georgia against Spanish invasions.

In summary, while none of the options provided are a perfect match, the Highland Scots are the most fitting choice based on their reputation for being fierce fighters, although they were not specifically organized for border protection.