Turn 8 subject marks into a couple of clear scores and explain what each component means.
New to this? See the worked example firstPCA turns many related columns into a few new ones that keep most of the information, such as turning 8 subject marks into an overall score and a science-versus-humanities score.
In these questions you read explained variance and loadings, decide how many components to keep, and score a new student.
If you are new to it, read the worked example first, then solve the questions in order: the early ones explore the data and train a first model, the middle ones test it on rows it has not seen, and the last ones tune it and turn the result into a business decision.