How does a hash$-$based message authentication code $($HMAC$)$ work? $($D$5,$ L$3\mathrm{.}3)$

Adding a nonsecret key value to the input function along with the source message

Adding a secret key value to the output function along with the source message

Adding a secret key value to the input function along with the source message

Adding a nonsecret key value to the output function along with the source message