Without relying on the use of any web servers in any way, select all choices with things that can be done completely in the web browser client using Javascript $($and HTML$/$CSS as is appropriate$).$

Question $6$ Select one or more:

a$.$

downloading a file

b$.$

uploading a file

c$.$

AJAX

d$.$

updating $($the currently loaded page's$)$ appearance

e$.$

dragging$-$and$-$dropping of items on the $($currently loaded$)$ page

f$.$

updating $($the currently loaded page's$)$ content