In symmetric key encryption schemes

Group of answer choices

a$)$ The sender and receiver use the same key to encrypt$/$decrypt data

b$)$ The sender and receiver use different keys to encrypt$/$decrypt data

c$)$ The sender and receiver must find a means to select$/$exchange a private key

d$)$ The sender and receiver can openly advertise their keys

e$)$ Parts a and c

f$)$ Parts b and d