What techniques can the researcher use when trying to overcome a respondent's inability to answer?

What will be an ideal response?

? To determine if respondents are informed, filter questions should be used to measure familiarity, product use, and past experience. The filter questions should be asked before questions about the topics themselves. A "don't know" option reduces uninformed responses without reducing overall response rate for questions. Hence, this option should be provided when the researcher expects that respondents may not be adequately informed about the subject of the question.
? To help the respondent remember, researchers should provide respondents with aids such as pictures, maps, and descriptions to help them articulate their responses.
? To help the respondent articulate responses, the researcher should provide the respondent various alternative descriptions of the area of interest so that the respondent could pick out the one they like best.