Step 1: Understanding the Concept:
A matching question is solved fastest by first fixing the pairs you are sure of. Then you can remove every option that contradicts them.
Step 2: Fix the sure pairs:
LinkedIn is the well known professional networking site, so C goes with IV. WhatsApp is a messaging service, so D goes with I. These two facts are enough to cut down the options.
Step 3: Use C-IV to remove options:
Options 1 and 4 give C as III and C as II. Both disagree with C-IV, so they are removed. Options 2 and 3 are left.
Step 4: Use D-I to separate the last two:
Option 3 pairs D with III, which is microblogging, and that clashes with D-I. Option 2 pairs D with I, so it agrees.
Step 5: Confirm the full code:
In option 2, Snapchat goes with the photo sharing application and X goes with the microblogging site. This is true, since Snapchat is built around pictures and X is built around short posts.
Final Answer:
Only option 2 agrees with all four correct pairs. \[ \boxed{\text{A-II, B-III, C-IV, D-I}} \]