The "Mosquito Ring Tone" Is Reported to Be __________

The "mosquito ring tone" is reported to be __________.

A) such a high frequency that most thirty- to forty-year-olds cannot hear it
B) such a low frequency that most thirty- to forty-year-olds cannot hear it
C) such a high frequency that most ten- to twenty-year-olds cannot hear it
D) such a low frequency that most ten- to twenty-year-olds cannot hear it