Step 1: Understand the question.
This is a matching question on net etiquette. Each of four etiquette words in List-I must be paired with the behaviour in List-II that best describes it.
Step 2: Match (B) Security.
Security is about keeping accounts and data safe from misuse. The only behaviour about protecting access is (I) Choose your password wisely. So B matches I.
Step 3: Match (D) Ethical.
Ethical behaviour means following rules and respecting the rights of others. Using someone's work without permission breaks those rules. So D matches (III) No copyright violation.
Step 4: Match (A) Credibility.
Credibility means being trusted for what you say. If you comment carelessly, people stop trusting you. So A matches (II) Cautious while making comments.
Step 5: Match (C) Reliability.
Reliability means others can depend on you. Being careful about what you upload, because it stays online and others may rely on it, fits (IV) Think before you upload anything. So C matches IV.
Step 6: Collect the pairs.
The full matching is A-II, B-I, C-IV, D-III.
Step 7: Check option 1.
It gives A-I, which is wrong, because a password is about security. Option 1 is wrong.
Step 8: Check option 2.
It gives A-I again and B-III. Both are wrong. Option 2 is wrong.
Step 9: Check option 3.
A-II, B-I, C-IV, D-III matches every pair above. Option 3 is correct.
Step 10: Check option 4.
It gives A-III and D-II, which are wrong. Option 4 is wrong.
Final Answer:
The correct matching is A-II, B-I, C-IV, D-III. This is option 3.
\[ \boxed{\text{(A)-(II), (B)-(I), (C)-(IV), (D)-(III)}} \]