Answer:
A. Surveying students about their favorite type of math problem; C. Sampling water for contaminants
Explanation:
Data gathering involves actually collecting data yourself instead of using data gathered beforehand by someone else.
In choice A, you are performing the survey yourself so you are gathering the data.
In choice B, you are using data found in a survey; this has been gathered by someone else, so you are not gathering the data.
In choice C, you are taking the sample yourself; this is gathering the data.
In choice D, you are making a chart using data already gathered; you are not gathering the data.
In choice E, you are finding the mean of data already gathered; this is not gathering the data yourself.
