What difficulties did Portugal face on the route between Portugal and India?

What difficulties did Portugal face on the route between Portugal and India?
 
  A) The Spanish sailors were constantly trying to inhibit their passage as a means of exploiting the trade for themselves, thus beginning a long series of wars between them.
  B) Scurvy and other diseases hindered the progress of the trade ventures.
  C) Powerful West African kings and armed Arabs in East Africa made it difficult to acquire necessary supplies to make the journey.
  D) The Portuguese encountered the most difficulties from mutinous crews on the incredibly arduous journey.
  E) The Portuguese encountered great difficulty in their passage due to Muslim merchant ships that did not want their trade undercut.