Answer:
option b and c are correct answers.
Explanation:
Let see each option in detail.
a) Sending email is not a risk.
b) Granting access is a problem because the other person can undermine the network
c) Unknow senders can send virus or other malicious code to corrupts you data.
d) Unwanted advertisement is not a big deal.
Answer:
Granting administrator access to a non-administrator
Opening files from unknown senders
Explanation:
Psst those are the answers