Identify the type of observational study (cross-sectional, retrospective, or prospective) described below. A research company uses a device to record the viewing habits of about 2500 households, and the data collected over the past 7 years will be used to determine whether the proportion of households tuned to a particular news program increased. Which type of observational study is described in the problem statement? A cross-sectional study A prospective study OA retrospective study