An educational psychologist wishes to investigate the impact of remote learning on student motivation in secondary schools across Greater Manchester. They obtain the complete directory of registered secondary school teachers from the local education authorities in Greater Manchester, select every 10th10^{\text{th}}10th teacher to receive a survey, and receive completed responses from 142 teachers. Which of the following elements from this study represents the sampling frame?
The target population of all secondary school teachers in Greater Manchester
The 142142142 teachers who completed and returned the survey
The complete directory of registered secondary school teachers from the local education authorities in Greater Manchester
The subset of teachers selected by taking every 10th10^{\text{th}}10th name from the directory
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.