The hydrogen spectral series are named by the principal quantum number of the lower energy level to which electrons transition. The Lyman series involves transitions to n=1 and produces UV radiation. The Balmer series involves transitions to n=2 and produces visible (and near UV) radiation. The Paschen series involves transitions to n=3 from higher levels (n=4, 5, 6,...) and produces infrared radiation, since the energy gaps are relatively small. The Brackett series involves transitions to n=4 and produces far infrared radiation. Therefore, transitions to n=3 define the Paschen series in the infrared. Option (A) is wrong because Lyman series terminates at n=1, not n=3. Option (B) is wrong because Balmer series terminates at n=2, and it produces visible light. Option (D) is wrong because Brackett series terminates at n=4. The series classification and their spectral regions are directly covered in NCERT and are high-frequency JEE theory questions. Plausibility check: as the lower-level quantum number increases, transitions involve smaller energy gaps, so Paschen (n=3) lies at lower energy (longer wavelength) than Balmer (n=2), correctly placing it in the infrared region.