Define the cellmembrane and cell

Cellmembrane=the semipermeable membrane surrounding the cytoplasm of a cell.

Cell=the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. Microscopic organisms typically consist of a single cell, which is either eukaryotic or prokaryotic.

characterization of nanoparticles is a critical step in nanomaterial production as it provides information of dimension, morphology, surface charge, distribution and degree of surface functionalization.

the answer to your question is b