Water found on an Exoplanet

Current context: For the first time, water has been discovered in the atmosphere of the exoplanet named K2-18b.

 

• Researchers have found both water and temperatures on K2-18b, being the only exoplanet having such components.
• The exoplanet is a planet orbiting a distant star outside our solar system.
• K2-18b is eight times the mass of Earth and about 110 light-years from the Earth in the Leo constellation.
• The team used the Hubble Space Telescope and developed open-source algorithms to analyse the starlight filtered through K2-18b's atmosphere.
• K2-18b is a cool exoplanet and receives only 5 per cent more radiation than the Earth.
• This planet is about the same temperature as Earth, but researchers are not confirmed that it is habitable or not.

Question: 

Q.1 Which exoplanet has been discovered recently to have water in its atmosphere?
a. K1-17b
b. K2-17b
c. K1-18b
d. K2-18b
e. K3-18b