An organ, such as the human liver, is made up of specialized that work together to perform a specific function.
a. nerves
b. tissues
c. fluids
d. glands

The bodys functions are conducted by organs. Each organ is a recongnizable structure that performs specific functions. An organ is made of several types of tissueand therefore several types of cells. So the correct answer is: B/ Tissues.

Cells make tissues, and tissues make organs. The human liver is a part of the organ system. The tissues that are used can be rough, smooth, fat, or skinny of whether you eat right or wrong. But everyone is different. So what I'm saying is that the answer is B. Tissues. 
Hope this helped!!! >.<