Which of the following would not prevent the issuance of a real estate license?

An applicant being only 18 years old would not prevent the issuance of a real estate license in California. The state allows individuals who are at least 18 years of age to apply for a real estate license, ensuring that younger adults can enter the profession, as long as they meet other necessary requirements.

In contrast, being a high school graduate may be beneficial, but this alone is not a mandatory requirement to obtain a real estate license. Having a misdemeanor could potentially complicate the licensing process; certain criminal backgrounds may require further review before an applicant can be licensed. Finally, failing the exam is a direct reason that would prevent the issuance of a license, as passing the required examination is a fundamental step in the licensing process. Thus, the criteria related to age specifically allows for individuals who are 18 or older to proceed with their application without restriction on that basis.