The Minimal Spanning Tree Solution Algorithm Works by Defining a Subnetwork

The minimal spanning tree solution algorithm works by defining a subnetwork and

A) adding the least expensive arc which connects any node in the current subnetwork to any node not in the current subnetwork.
B) adding the most expensive arc which connects any node in the current subnetwork to any node not in the current subnetwork.
C) adding the least expensive arc which connects unconnected nodes in the current subnetwork.
D) adding the least expensive arc which connects the most recently added node in the current subnetwork to the closest node not in the current subnetwork.