Final answer:
The statement in the question is true. If the Ac element transposes to a site that has not yet replicated, it will result in a decrease in number.
Step-by-step explanation:
The statement in the question is true. If the Ac element transposes to a site that has not yet replicated, it will result in a decrease in number. The Ac element provides the transposase enzyme required for transposition, and when it moves to a new site, it takes the Ds element with it. This means that both the Ac and Ds elements will be present at the new site, resulting in an increase in their number if the site has already replicated.