This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
All are true about iliolumbar ligament, except 
Select and explain. 
A. Attached to transverse process of L4, B. Lower part attached to sacrospinous ligament, C. It is attached to iliac crest, D. Superiorly continuous with thoracolumbar fascia
B: Lower part attached to sacrospinous ligament
Answer: B: Lower part attached to sacrospinous ligament 
Explanation: Ref. Gray’s anatomy.  41st edition. Page. 1090
 
Ilio-Lumbar Ligament:
The portion of the iliolumbar ligament originating from the L-5 transverse process is made up of two bands (anterior and posterior).
The anterior band is broad and flat and has two different anatomic varieties. 

Type 1 originates from the anterior aspect of the inferolateral portion of the L-5 transverse process and fans out widely before inserting on the anterior portion of the iliac tuberosity.
Type 2 originates anteriorly, laterally, and posteriorly from inferolateral aspect of the L-5 transverse process and fans out before inserting on the anterior portion of the iliac tuberosity.

 It is probable that the spatial disposition of the iliolumbar ligament influences its antitorsional role
Origin: transverse process of L5
insertion: deep into ventral margin of iliac crest 6-7cm from midline
The main part of ILL originates from L5 transverse processes. insert was shield by crest dorsally,making it inaccessable to palpation.