答案：D

解析：

By the Triangle Inequality, the sum of the lengths of any two sides of a triangle must be greater than the length of the remaining side. Therefore, BC + AB greater than AC, or 2 + AB greater than 12. Thus, AB greater than 10, which eliminates options (A), (B), and (C). Also by the Triangle Inequality, BC + AC greater than AB, or 14 greater than AB, which eliminates choice (E). Therefore, of the given choices, only choice (D), 12, could be the length of side line AB.