Answer the following question given this paragraph: 

The second main component of plasma membranes are the variety of proteins. A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. Membrane proteins can be put into two groups based on how the protein is associated with the membrane: (1) integral membrane proteins and (2) peripheral membrane proteins.


Q: What type of protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle?

 Choices:

- amino acid

- rod protein

- conduction protein

- membrane protein

A:
membrane protein
