What challenge is presented by a small wire-loop antenna for direction finding?

A small wire-loop antenna produces a "figure-eight" radiation pattern. This pattern features two very sharp and deep nulls (points of minimum signal reception) that are located broadside, or perpendicular, to the plane of the loop. For direction finding, operators typically hunt for these nulls rather than the signal peaks because the nulls are much narrower and provide a more precise bearing. However, this creates a specific challenge: because there are two identical nulls exactly 180 degrees apart, the antenna provides a bidirectional null pattern. This means the operator can determine the line of bearing, but cannot immediately tell which of the two opposite directions the signal is coming from without the use of an additional "sense" antenna. Understanding the actual characteristics of a small loop helps eliminate the distractors. Option B is wrong because the nulls of a small loop are highly defined, which is exactly why they are used for finding bearings. Option C is false because small loop antennas are highly practical and historically very common for direction finding on HF, MF, and LF bands, not just VHF and higher.