The correct option is A 10 to 20 days
Life cycle of Plasmodium is completed in two hosts. Man is considered primary host in which schizogony occurs in liver and blood, and female Anopheles mosquito is the secondary host in which the gametogony and sporogony takes place. This life cycle in mosquito is completed in 10-20 days.
Thus, the correct answer is option (A), '10 to 20 days'.