Excessive artificial night lighting poses the greatest hindrance to astronomers attempting to study which of the following astronomical phenomena?

The correct answer is: Distant, low-luminosity galaxies and deep-sky nebulae

Explanation:
Excessive artificial night lighting is the primary cause of light pollution, particularly a phenomenon called skyglow. Skyglow happens when artificial light from outdoor fixtures shines upward into the atmosphere, scattering off air molecules, dust, and aerosols, which brightens the night sky baseline.

Distant, low-luminosity galaxies and deep-sky nebulae are extraordinarily faint objects that emit very little photons that reach Earth telescopes. To observe or capture images of these faint astronomical bodies, astronomers require high visual contrast against a truly dark background sky. When skyglow increases the ambient light level of the background sky, the contrast is severely degraded, washing out the delicate detail and faint light of these distant objects.

Why other options are unaffected or less hindered:
• The lunar cycle and its changing phases: The Moon is extremely bright, making its phases easily visible even from brightly lit city centers.
• Daytime meteor showers: These occur during daylight hours, where the primary factor is sunlight rather than night lighting.
• Total eclipses of the Sun: Solar eclipses are daytime events caused by the Moon blocking the Sun's disk, so artificial night lighting plays no role in observing them.