When a skin graft (called a "free flap graft") is disconnected from the vascular and nervous supply, this is coded using the root operation of?

The answer would be the replacement

Replacement in ICD-10 can be defined as putting a material (biological or synthetic) that takes the place or function of a portion of a body part. 
A skin graft is collected from a part of the body to cover another part that needs the skin so it should be a replacement operation.
Other examples would be bone graft, valve replacement, or total knee replacement. 

Centration is the correct answer

The gens present in the dna in the nucleus of the cell in the body