Which statement correctly contrasts shielded twisted pair (STP) and unshielded twisted pair (UTP) cables?

• A. STP uses shielding to mitigate EMI; UTP is cheaper and suitable in low-interference environments.
• B. UTP provides shielding against EMI while STP does not.
• C. Both STP and UTP offer identical interference protection.
• D. STP is always preferred in all environments due to its low cost.

Answer: (A)

Shielding around the pairs is what gives STP its extra protection. The metal shield blocks external electromagnetic interference and reduces crosstalk, with the shield typically connected to ground to drain away noise. Unshielded twisted pair, by contrast, has no shield, so it relies solely on the twisting of the wires to cancel interference. That makes UTP cheaper and easier to install, but more vulnerable in noisy environments or on longer runs. So the statement that STP uses shielding to mitigate EMI and UTP is cheaper and suitable in low-interference environments matches how these cables behave in practice. The other options misstate the relationship—UTP doesn’t provide shielding, STP isn’t universally better or cheaper in every scenario, and they do not offer identical interference protection.