We do not transmit low frequency signals to long distances because:
$(a)$ The size of the antenna should be comparable to signal wavelength,which is impractical for a signal of longer wavelength.
$(b)$ Effective power radiated by a long wavelength baseband signal would be high.
$(c)$ We want to avoid mixing up signals transmitted by different transmitters simultaneously.
$(d)$ Low frequency signals can be sent to long distances by superimposing them with a high frequency wave.
Therefore,the most suitable options are:

• A
  All statements are true
• B
  $(a), (b)$ and $(c)$ are true only
• C
  $(a), (c)$ and $(d)$ are true only
• D
  $(b), (c)$ and $(d)$ are true only