Which feature differentiates Unshielded Twisted Pair (UTP) from Shielded Twisted Pair (STP)?

Unshielded Twisted Pair (UTP) is characterized primarily by the absence of any shielding around the twisted pairs of wires. This lack of shielding means that UTP is more susceptible to electromagnetic interference (EMI) compared to Shielded Twisted Pair (STP), which includes an additional layer of shielding that protects the wire pairs from such interference. This fundamental difference in design makes UTP suitable for many applications, especially in environments with low levels of interference, but makes STP a preferable choice in settings where interference could be more pronounced.

The other options suggest characteristics of UTP that do not accurately highlight its differentiating factor from STP. The use of multiple solid wires can apply to both types of cabling, and while UTP is generally lighter due to the absence of shielding, this is not a definitive or essential factor that differentiates it. Furthermore, the claim that UTP cables are only used indoors is misleading, as they can be used both indoors and outdoors, although specific types of UTP are designed for particular environments.