I believe 4 would be incorrect.
The correct answer is: A) hold a difficult ballet pose.
Here we are talking about flexibility which refers to the ability to bend easily without hurting oneself. If you are flexible it means that you are able to strech easily. There are various types of streches.
In this case the static steching refers to a position that is held for a period of time, usually between 10 to 30 seconds. Although it is a challenging position it is generally the most confortable type of streching. In ballet, difficult poses are constantly held in the trainings which means they use static streching.
The other options refer to other types of flexibility, like the dynamic in which you move through a range of motion repeatedly, the golf swing can be used here. Or avtive flexibility in which you strech a muscle by activately contracting the muscle in opposition.
