નીચે આપેલા વાક્યના હાઇલાઇટ કરેલા ભાગને સુધારો:
The reason $why\, he\, wrote\, the\, letter\, was\, because$ he could not contact him over the phone.

• A
  why he wrote the letter was since
• B
  for which he wrote the letter because
• C
  why he wrote the letter was that
• D
  No improvement