Which of the Following Is an Example of Phase Variation

Multiple Choice

Which of the following is an example of phase variation?

A) N. gonorrhoeae expressing different types of pilin protein.
B) Influenza virus expressing variations of glycoprotein HA and NA spikes.
C) S. pyogenes producing a capsule of hyaluronic acid, which is also a host component.
D) E. coli producing pili for attachment to epithelial cells.
E) These are all examples of phase variation.