Over a one-month period, a researcher recruited 200 men and women over the age of 60 from the lobby at Lifestyle Fitness, and asked them to complete a survey about their attitudes toward physical fitness. She found that the majority of participants believed that senior citizens should attend the gym at least 3 times a week. She concluded that senior citizens have a very positive attitude toward fitness and health. Which of the following is true?

A) Because she surveyed so many people, her findings can be generalized to seniors in the general population

B) Her sample is a biased one, because her sample was not a random one

C) Both a. and b. are true

D) Neither a. nor b. is true