Step 1: Understand the question.
We need the technique that improves how accurate a search engine result is.
Step 2: The search problem.
Search engines look through billions of pages. To get only the useful ones, we must shape the query smartly.
Step 3: Meet Boolean operators.
Boolean operators are the words AND, OR, and NOT. They tell the search engine how the keywords should relate.
Step 4: How they refine results.
AND keeps pages with all the words, OR widens to pages with any word, and NOT removes pages with an unwanted word. This makes results sharper.
Step 5: Reject the other options.
Long paragraphs, typing in uppercase only, or avoiding keywords do not help and can even hurt the search.
Step 6: Conclude.
So the best technique is using Boolean operators (AND, OR, NOT), which is option 2.
\[ \boxed{\text{Boolean Operators (AND, OR, NOT)}} \]