Evaluate competing hypotheses for dark matter composition—particle candidates (WIMPs, axions, sterile neutrinos), compact objects (MACHOs), and modified gravity (MOND/TeVeS)—by comparing their theoretical predictions to key observations: galactic rotation curves, gravitational lensing, CMB anisotropies, large-scale structure, and direct/indirect detection and microlensing limits. Weigh strengths and weaknesses, identify discriminating tests, and justify which hypothesis best fits current evidence.