A Sex Researcher Is Interested in Understanding the Trends in Contraceptive

A sex researcher is interested in understanding the trends in contraceptive use among women living in the United States.For this purpose, he obtains a convenience sample of 70 sexually-active 21-year-old females across the country.However, upon closer investigation, it was discovered that all the participants had one characteristic in common-they all had engaged in intercourse before the age of 15.Based on this we may conclude that:

A) the sample is highly representative of the entire female population of the country.
B) the results obtained from the study may not be true of all 21-year-old females.
C) the results obtained from the study are free from volunteer bias.
D) the results obtained from the study may be extrapolated to the population.