Answer:
Segment BF = 16 is true.
Step-by-step explanation:
Since, DE is parallel to BC, so DE will divide AB and AC proportionally.
Hence,

⇒
{Since, given that AE = 12, EC = 18 and AD = 6}
⇒ BD = 9.
Again, since, EF is parallel to AB, so EF will divide BC and AC proportionally.
Hence, 
⇒
{Since, given that AE = 12, EC = 18 and FC= 24}
⇒ BF = 16.
Therefore, segment BF = 16 is true. (Answer)