#### Answer

SAS

#### Work Step by Step

Lowercase letters represent sides of the triangle while uppercase letters represent angles of the triangle.
Since a,b and C are given, this means that two sides and one angle is given. In addition, the angle C is the included angle as it is between a and b.
Therefore, it is clear that SAS is given since SAS refers to side-angle-side where the given angle is between the two given sides.