Answer
If the strands of hair are positively charged, the hairs will exert a repelling force on each other, which pushes the hairs as far away from each other as possible. Since the hairs are still attached to the head, the farthest the hairs can get from each other is to move straight out from the head radially.
Work Step by Step
Hair loses electrons very easily and the strands of hair become positively charged when they lose electrons. If the strands of hair are positively charged, the hairs will exert a repelling force on each other, which pushes the hairs as far away from each other as possible. Since the hairs are still attached to the head, the farthest the hairs can get from each other is to move straight out from the head radially.
