Which of the following best describes the effect of a non-compete clause?

The best description of the effect of a non-compete clause is that it restricts former employees from competing for a specified period. Non-compete clauses are legal agreements that limit an employee's ability to join or start a competing business within a certain geographic area and timeframe after leaving the employer. This restriction aims to protect the employer's interests by preventing former employees from leveraging confidential information, specialized training, or significant business relationships gained during their employment to the detriment of the employer. Such clauses are put in place to maintain competitive advantage and safeguard sensitive information, ultimately impacting how and where former employees can work thereafter.

The other options don't accurately capture the essence of a non-compete clause. For instance, flexibility for former employees is generally not associated with this kind of agreement, and sharing business secrets is contrary to the purpose of these clauses. Similarly, saying there is no real impact on employee mobility understates the significant limitations that such clauses impose on employment opportunities for those who sign them.