Final answer:
The County Executive Committee in Texas primarily functions to coordinate local party activities, such as voter and donor mobilization, candidate training, and party member recruitment.
Step-by-step explanation:
One of the key functions of the County Executive Committee in Texas is C) Coordinating local party activities. This includes identifying and mobilizing potential voters and donors, identifying and training potential candidates for public office, and recruiting new members for the party. County organizations often take on the roles of organizing volunteers for Election Day, ensuring that elections are conducted fairly, and holding regular meetings for members to meet candidates and coordinate strategy.