While testing the chemiosmotic theory across the domains of life, researchers prepared "inside-out" vesicles from bacterial plasma membranes, mitochondrial internal membranes, and chloroplast thylakoids. An inside-out vesicle is a

A) vesicle in which the F1 subunit of the proton-ATPase faces outward.
B) membrane in which the hydrophobic tails of the phospholipids face outward.
C) cell that has been enzymatically stripped of its cell wall.
D) preparation of outer membranes in Gram-negative bacteria, chloroplast envelopes, and mitochondria outer membranes.
E) preparation from bacterial cytoplasm, chloroplast stroma, and mitochondrial matrix.