Which situation is an example of Lev Vygotsky's concept of scaffolding?

Ranjan can do math problems up to second-grade level on her own, but she needs help doing problems at fourth-grade level.

Ranjan understands that a ball of clay contains the same amount of clay when flattened as it did in the original ball shape.

Ranjan's mother works one on one with her on a new task but gradually helps less and less, as Ranjan becomes more skilled and capable.

Ranjan works alone on a task until she masters it.