The germ layer destined to become the inner lining of body organs is the endoderm.

Here's a breakdown:

* Endoderm: Forms the lining of the digestive and respiratory systems, as well as the organs associated with them (liver, pancreas, etc.). It also gives rise to the urinary bladder and urethra.

* Mesoderm: Forms muscles, bones, blood, and other connective tissues.

* Ectoderm: Forms the skin, nervous system, and sensory organs.

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