A. January 2020
B. March 2020
C. May 2020
D. None of these

Explanation:

The World Health Organization (WHO) declared Covid-19 a global pandemic on March 11, 2020 (B), due to its widespread impact. The virus was identified earlier, but the official pandemic declaration came in March, not January (A) or May (C). “None of these” (D) is incorrect because B is the correct answer.

Correct Answer: B. March 2020

The correct answer to the question: "The Covid-19 was officially declared a global pandemic by the WHO in: ____________?" is "March 2020".