Annabelle wanted to find out how many people in her neighborhood were going to the rock concert over the weekend. She asked a couple of her immediate neighbors. On the basis of the answers she got, she drew her conclusion. What kind of statistical investigation did Annabelle perform? survey

This is a convenience sample, as a convenience sample is identified as a type of sample that surveys easy-to-obtain members, so for instance, your neighbors are quite easy to obtain for the survey as you might know them to an extent more than strangers across your neighborhood and you live near each other, so this is a convenience sample.