E8C12:What factors affect the bandwidth of a transmitted CW signal?
Direct answer summary (2024-2028 NCVEC pool)
The official correct answer for E8C12 is Keying speed and shape factor (rise and fall time).
The key fact is Keying speed and shape factor (rise and fall time). Match that fact to the exact condition in the question; the other choices describe a different rule, band, component, or operating situation.