Which of the following is the Galilean moon that was observed in 1610 by the Italian astronomer Galileo Galilei using a homemade telescope?

Ganymede

The correct answer is Option (4) - Ganymede

Ganymede is one of the four largest moons of Jupiter and the largest moon in the solar system. It was first observed by the Italian astronomer Galileo Galilei in 1610 using a homemade telescope. Ganymede is notable for being the only moon known to have its own magnetic field and for being larger than the planet Mercury. It has fascinated astronomers and space enthusiasts for centuries due to its unique characteristics and its potential for harboring subsurface oceans, making it a key target for future exploration missions.