The correct statement about the new style of architecture in Rome in the 15th century is option 2. This new style of architecture was actually a revival of the imperial Roman style. It sought to recreate the grandeur and magnificence of ancient Rome through the use of classical architectural elements, such as columns, arches, and domes.

Option 1, which states that the new style was marked by a complete break from the past, is incorrect. The architecture of this period was heavily influenced by classical Roman architecture, and therefore can be seen as a continuation or revival of the past rather than a break from it.

Option 3, which states that architects familiar with the classical style were employed by wealthy merchants and aristocrats, is also correct. These wealthy patrons sought to showcase their wealth and status by commissioning grand buildings in the classical style, and they hired architects who were well-versed in this style to create these structures.

In summary, while option 1 is incorrect, options 2 and 3 are correct explanations of the new style of architecture in Rome in the 15th century.