{"knowledge_schema": {"broad_category": "Astrophysics \u2192 Cosmology \u2192 Distance Measurement", "refinement": "This problem involves calculating the comoving distance to a quasar based on cosmological parameters defined by the Lambda-CDM model.", "specific_scope": "The focus is on determining the comoving distance at a scale factor of a=1, using the Hubble constant and density parameters provided.", "goal": "Identify the correct comoving distance value from the given options based on the cosmological model."}, "summary": "This problem pertains to astrophysics and cosmology, specifically the measurement of comoving distances in a universe described by the Lambda-CDM model. Given the Hubble constant and density parameters, the task is to determine the comoving distance to a quasar at a scale factor of a=1. The correct answer, based on the calculations and assumptions of the model, is 8 Gpc."}