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Answer: Independent Samples t-test
Explanation:
The independent samples t test, also called an unpaired samples t test, is used to compare two sets of data from samples that are independent.
This experiment compares two sets of data, the grades from the group of learners that took the course in the old format and the group that took it in the new format, to see if the grades differ depending on the format of the course.
The one sample t test wouldn´t be correct because it´s used to compare one result with an expected value. And the paired t test wouldn´t be correct because it´s used to compare related observations, such as test scores from a test taken at different hours of the day.