Kelsey plays soccer and gets grass stains on her shorts. She uses several types of laundry detergent to try to remove the stains, but none of them work. She makes the hypothesis that laundry detergents are not able to remove grass stains from clothing. Which best describes the evidence that fails to support the hypothesis

Donald is studying the eating habits of all students attending his school. he samples the population by dividing the students into groups by grade level and randomly selecting a proportionate number of students from each group. he then collects data from the sample. which type of sampling is used? select the correct answer below: systematic sampling convenience sampling stratified sampling cluster sampling