**Core Concept**
The development of antimicrobial resistance in frequent lens users is related to the use of antimicrobial agents in contact lens care products, which can lead to the selection and proliferation of resistant microorganisms.

**Why the Correct Answer is Right**
The primary mechanism behind this phenomenon is the overuse and misuse of antimicrobial agents, such as chlorhexidine and polyquaternium-1, in contact lens care products. These agents can disrupt the normal bacterial flora and select for resistant strains, particularly Pseudomonas aeruginosa, which is a common cause of contact lens-related infections. The repeated exposure to these antimicrobial agents can lead to the development of resistance through various mechanisms, including genetic mutations and the transfer of resistance genes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the development of antimicrobial resistance in frequent lens users. While antibiotic resistance is a broader public health concern, it is not directly related to the use of contact lenses.

**Option B:** This option is incorrect because the primary cause of antimicrobial resistance in frequent lens users is not the use of contact lenses themselves, but rather the antimicrobial agents used in their care.

**Option C:** This option is not directly related to the development of antimicrobial resistance in frequent lens users. While contact lens wear can increase the risk of eye infections, the primary concern is the antimicrobial resistance associated with the use of antimicrobial agents in contact lens care products.

**Clinical Pearl / High-Yield Fact**
Frequent lens users should follow proper contact lens hygiene and care practices, including cleaning and disinfecting their lenses regularly, to minimize the risk of developing antimicrobial resistance and related eye infections.

**Correct Answer: C. The use of antimicrobial agents in contact lens care products.**