Why Was It Difficult for Spanish and Portuguese Mariners to Return

Multiple Choice

Why was it difficult for Spanish and Portuguese mariners to return home from the Canary Islands?

A) They had to sail against the winds.
B) Unusual magnetic fields in that area rendered navigational instruments useless.
C) Berber pirates preyed on ships sailing northward from the Canaries.
D) They had no knowledge of the tacking maneuver.