Step 1: Understanding the concept:
A Public Relations Officer (PRO) manages how the public and media see an organisation. The job is about reputation, trust and communication, not about selling or running paid ads.
Step 2: Check A, AD campaign design:
Designing ad campaigns is the work of advertising or creative teams, who buy space and time. A PRO may support them, but it is not the core duty. So A is not a PRO duty.
Step 3: Check B, Crisis management:
When bad news hits, the PRO speaks to media, issues statements and protects the name of the organisation. So B is a PRO duty.
Step 4: Check C, Building brand image:
Creating a good public image through press notes, events and relations with media is the heart of PR. So C is a PRO duty.
Step 5: Check D, Expanding business with partners:
Finding partners and growing business is a business development or marketing task. So D is not a PRO duty.
Step 6: Choose the option:
Only B and C are PRO duties, which is option 3.
Final Answer:
B and C only, option 3.
\[ \boxed{\text{Option 3: B and C only}} \]