Theorem: A line parallel to one side of a triangle divides the other two proportionately.

In the figure below, segment DE is parallel to segment BC and segment EF is parallel to AB:

The figure shows triangle ABC with segments DE and DF. Point D is on side AB, point E is on side AC and point F is on side BC.

Which statement can be proved true using the given theorem?

Segment BF = 9
Segment BD = 18
Segment BD = 20
Segment BF = 24