Which kind of tumor grows slowly and is surrounded by membranes that prevent it from spreading from the original site?

It is the benign tumor. It is classified as a tumor for its abnormal reproduction of cells, but unlike malignant or cancerous tumors, it doesn't spread, and it can be removed as well.

The correct answer is a benign tumor.

A benign tumor refers to a tumor (mass of cells) that is non-cancerous and grows slowly. A benign tumor is surrounded by membranes that stop it from spreading to other parts of the body, unlike malignant (cancer forming) tumors that can easily spread to other parts of the body. 

Ithink it true i might be wrong so don't take my word that its true.

They break down fat