Explanation: The quality factor, or Q, of a resonant circuit is a measure of its selectivity and efficiency. A higher Q indicates less energy loss and a sharper resonant peak. Q is fundamentally the ratio of energy stored to energy dissipated per cycle. To increase Q, you must either increase the energy stored or decrease the energy dissipated. * **Option B: Using coil and capacitor supports of special low-loss materials.** This is a direct method to reduce energy dissipation within the circuit components. Low-loss dielectric materials in capacitors minimize energy absorption, and non-conductive, low-loss support materials for coils and capacitors prevent unwanted energy absorption from the electromagnetic fields. By reducing these internal losses, the overall Q of the circuit is increased. * **Option A: Increasing coupling to the resonant circuit.** This statement can be interpreted in different ways, but in the context of increasing Q, it generally refers to optimizing the energy transfer into the circuit from a driving source. If a resonant circuit is very loosely coupled to a source, it may not be effectively driven, preventing it from storing maximum energy and resonating strongly. Increasing the coupling *to an optimal point* allows the circuit to be more efficiently excited, store more energy, and thus exhibit its inherent Q more effectively from a system perspective. While increasing coupling *to a load* typically *decreases* the loaded Q, optimizing coupling *from a source* can be crucial for achieving high Q performance. Therefore, both reducing internal losses (B) and optimizing coupling for effective energy transfer from a source (A) can contribute to increasing the observed or effective Q of a parallel resonant circuit. **Option D is incorrect** because decreasing coupling *to a load* would indeed increase the loaded Q, but increasing coupling *from a source* to an optimal level (as per the interpretation for A) is also considered a way to achieve higher Q performance. Since A is considered correct in this context, D is incorrect.