This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
A person with prolonged usage of contact lenses presented with irritation of left eye. A diagnosis of keratitis was made and corneal scrapings revealed growth of multidrug resistant pseudomonas aeroginosa. Which of the following, best explains the mechanism of antimicrobial resistance in these isolated pseudomonas aeroginosa strains? 
Select and explain. 
A. Improper contact lens hygiene, B. Ability of Pseudomonas to produce biofilms, C. Frequent and injudicious use of topical antibiotics, D. Ability to transfer resistance genes from adjacent commensal flora
B: Ability of Pseudomonas to produce biofilms
Answer: B: Ability of Pseudomonas to produce biofilms 
Explanation: Pseudomonas aeruginosa and streptococcus pneumoniae are common nosocomial pathogens well known for their ability to aggregate and form biofilms. Cells which form biofilm are not susceptible to host immunity. If a microbe successfully forms a biofilm, it will be biocide-resistant and hence highly virulent. Ref: Contact Lens Practice By Nathan Efron, 2002, Chapter 39; Biofilm Eradication and Prevention : A Pharmaceutical Approach to Medical Device Infections, Page 69, 177; Textbook of Ophthalmology By Sunita Agarwal, Athiya Agarwal, David J Apple, 2002, Pages 216, 1007; Microbiology By Richard A. Harvey, Pamela C. Champe, Bruce D. Fisher, William A. Strohl, 2nd Edition, Page 139