Consider the following statements regarding gymnosperms and choose the correct option.
I. In gymnosperms, the male and female gametophytes have an independent existence.
II. In gymnosperms, the multicellular female gametophyte is retained within the megasporangium.
III. All gymnosperms are heterosporous.
Of these statements
 

• A

  I and II are true but III is false

• B

  I and III are true but II is false

• C

  II and III are false but I is true

• D

  II and III are true but I is false