Q. Which climatic phenomenon is characterized by cooler than normal sea surface temperatures in the central Pacific Ocean?

The correct answer is: a) La Nina

Explanation: La Nina is a climatic phenomenon characterized by cooler than normal sea surface temperatures in the central and eastern Pacific Ocean, near the equator. It is part of the El Nino-Southern Oscillation (ENSO) cycle, which includes both La Nina (cooling phase) and El Nino (warming phase). La Nina typically influences global weather patterns, often leading to increased rainfall in some regions and droughts in others.

The other options do not describe this specific phenomenon. El Nino refers to warmer sea surface temperatures, Monsoon is a seasonal wind pattern, and Tornado is a localized weather event involving rotating winds.