A(n) is usually a long binary number that is used with the encryption algorithm to ""lock"" the characters of the message being protected so that they are undecipherable without the number.

A key

Explanation:

it could be e. idk for sure

assuming you are in the home page.

1) go to the upper right hand corner

2) click on your "profile picture"

3) go down to "edit profile"

4) it should be titled as "edit your profile", click on "profile picture"

5) choose a file

6) press "change"

you're profile picture is updated

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