Final answer:
The primary indicator of a well-whipped Italian meringue is the formation of stiff peaks, with a secondary sign being its glossy texture.
Step-by-step explanation:
The main indicator that an Italian meringue has been whipped long enough is a) Stiff peaks. When the meringue is whipped sufficiently, it will form stiff, upright peaks that hold their shape when the whisk is lifted. A secondary characteristic of a properly whipped Italian meringue is a b) Glossy texture, which indicates that the sugar has been fully dissolved and incorporated. The aroma and color change are not reliable indicators for Italian meringue readiness.