Concept:
Bile is an important digestive secretion that helps in digestion and absorption of fats.
Step 1: Formation of bile.
Bile is produced by the liver.
Step 2: Storage of bile.
After formation, bile is stored and concentrated in the gall bladder.
Step 3: Release during digestion.
When fatty food enters the small intestine, gall bladder releases bile into the duodenum.
Step 4: Checking other options.
Liver produces bile but does not store it mainly.
Pancreas secretes digestive enzymes.
Spleen filters blood.
Gall bladder stores bile.
\[
\boxed{\text{Gall bladder}}
\]