Answer : 3. "higher frequency"
Explanation :

Answer: C) higher frequency Explanation: As the frequency of sound is higher, women have shriller voices than men. The shrillness or pitch of a sound is determined by its frequency. The higher the pitch shriller the voice. As the sounds produced by vocal cords of women are higher than men so women have shriller voices than men. Because their vocal cord is of smaller size. As their vocal cord is more stretched than men's.