Final answer:
Frontal plane motion occurs around the transverse axis, with the frontal or coronal plane dividing the body into anterior and posterior portions.
So, the correct answer is 1) Transverse axis.
Step-by-step explanation:
The motion in the frontal plane occurs around the transverse axis. The frontal plane, also known as the coronal plane, divides the body or an organ into anterior (front) and posterior (rear) portions. Movements such as abduction and adduction of the limbs happen within the frontal plane. These are side-to-side movements, where abduction moves a limb away from the midline of the body and adduction moves it towards the midline.
So, the correct answer is 1) Transverse axis.