A carrier is phase modulated (PM) with frequency deviation of $10 \; \mathrm{kHz}$ by a single tone frequency of $1 \; \mathrm{kHz}$. If the single tone frequency is increased to $2 \; \mathrm{kHz}$, assuming that phase deviation remains unchanged, the bandwidth of the PM signal is
- $21 \; \mathrm{kHz}$
- $22 \; \mathrm{kHz}$
- $42 \; \mathrm{kHz}$
- $44 \; \mathrm{kHz}$