Concept:
WHO stands for the World Health Organization, which is a specialized agency of the United Nations responsible for international public health.
It was established in 1948 and works to:
• Promote global health
• Prevent diseases
• Improve healthcare systems
• Coordinate international health activities
Step 1: Analyze option A.
“World Healthy Operation” is not the correct expansion of WHO.
Hence, option A is incorrect.
Step 2: Analyze option B.
“World Health Office” is not the official full form of WHO.
Hence, option B is incorrect.
Step 3: Analyze option C.
“Worldwide Hospital Organization” is not related to WHO.
Hence, option C is incorrect.
Step 4: Analyze option D.
WHO correctly stands for:
\[
\text{World Health Organization}
\]
Hence, option D is correct.
Therefore, the correct answer is:
\[
\boxed{(D)\ \text{World Health Organization}}
\]