a$)$ What is a $.$gitignore file? $(3$ points$)$

b$)$ What is the Git command you can use to compare two commits? $(3$ points$)$

c$)$ What is the HEAD pointer in Git and how does it move around? $(3$ points$)$

d$)$ What Git command can you use to undo changes to a file in your working directory?

$(3$ points$)$

e$)$ What Git command can you use to revert a commit? $(3$ points$)$