Answer:a. Web and e-mail
Explanation:A survey is a method of gathering information from a number of individuals, known as a sample, in order to learn something about the larger population from which the sample is drawn.
Web surveys or internet surveys are defined as a data collection method where surveys or questionnaires are sent over the internet to a sample of respondents and they can respond to this survey over the world wide web. Respondents can be sent web surveys via various mediums such as email, embedded over the website, social media, etc. In web surveys, respondents answer the questionnaire with the help of a web browser and the survey responses are stored in web-based databases.