Which transmission media is more efficient than two-wire lines for transferring electromagnetic energy?

Coaxial lines are recognized for their superior efficiency in transferring electromagnetic energy compared to two-wire lines. The construction of coaxial cables, which features a central conductor surrounded by an insulating layer and an outer conductive shield, reduces electromagnetic interference and crosstalk. This design leads to higher bandwidth and improved signal integrity, making coaxial cables effectively suited for applications that require high-frequency signals, such as cable television and internet connections.

Additionally, coaxial lines can carry a larger amount of data over longer distances than traditional two-wire lines, which are limited by inductance and resistance factors. In contrast, while fiber optic cables provide excellent transmission capabilities as well, they utilize light rather than electromagnetic energy, which sets them apart from the focus on the electromagnetic efficiency within this question. Open-wire lines and twisted pair cables are generally less efficient than coaxial lines due to higher susceptibility to interference and signal degradation. Thus, coaxial lines stand out for their effectiveness in transmitting electromagnetic energy, justifying their selection as the correct answer.