Some of the Most Powerful Research Conclusions Have Been Drawn

Some of the most powerful research conclusions have been drawn from studies that have included both quantitative and qualitative elements.Which of the following contains both elements?

A) Collecting pre-test and post-test data.
B) Collecting data from an achievement test and an aptitude test.
C) Collecting student grades and teacher comments.
D) Collecting student comments and teacher comments.
E) Collecting data from video recordings and written summaries of student journal entries.