When data of the variable is collected at distinct time intervals for a specified period of time, it is called

When data of a variable is collected at distinct time intervals for a specified period of time, it is called time series data.

The key phrase "collected at distinct time intervals for a specified period of time" directly defines time series data. This refers to data points recorded at different points in time over some duration.

Examples of time series data:

Recording a student's math scores every month for 1 year tracks performance over time.

Recording temperature every hour for one day tracks temperature over time intervals.

Recording a company's stock price every day for a year tracks prices over time.

Cross-sectional data is collected at one single point in time from different subjects. For example, exam scores of all students in a class on one particular day. This does not involve time intervals.

Pooled data combines both cross-sectional and time series data together.

Constant data refers to data that doesn't change and is not a standard statistical term for data classification.

Therefore, the answer is Option 2 - Time series data.