What is an advantage of using I-Q modulation with software-defined radios (SDRs)?

The primary advantage of I-Q (In-phase and Quadrature) modulation in Software-Defined Radios is its incredible versatility. By mathematically manipulating the amplitude of the I and Q signals, which are 90 degrees out of phase, a digital signal processor can generate any combination of phase, frequency, or amplitude. This means that AM, FM, SSB, CW, and complex digital modes can all be created purely in software using the exact same hardware platform. The other options are incorrect: I-Q modulation actually relies heavily on high-resolution analog-to-digital converters, it does not inherently reduce the minimum detectible signal level, and digital-to-analog conversion is a hardware function rather than an automatic benefit of I-Q modulation.