Researchers Studying the Rigidity and Fexibility of the Cell Envelope

Researchers studying the rigidity and fexibility of the cell envelope used chemotaxis to measure the ability of microbes to squeeze through tight spaces. E. coli, a gram-negative bacterium, was able to traverse narrower channels than B. subtilis, a gram-positive microbe, even though both cells are the same size when grown without restriction. E. coli has the more fexible cell envelope because _______.

A) it has fewer flagella
B) there are fewer protein receptors
C) it has only a single membrane
D) lipopolysaccharide has no charge
E) there is less structural carbohydrate