Out of the given options, three are similar in a certain manner. However, one option is NOT like the other three. Select the option which is different from the rest.

Let's analyze the meaning and category of each options:

Option (a): Galaxy

A massive system consisting of billions of stars, gas, dust, and dark matter, bound by gravity.

Option (b):  Constellation

A group of stars forming a recognizable pattern, usually named after mythological characters, animals, etc.

Not a physical group — it’s based on visual appearance from Earth.

Option (c): Star

A luminous celestial body made of plasma, like our Sun. The basic unit present in galaxies, solar systems, and constellations.

Option (d):  Solar system

A system of planets, moons, asteroids, etc., orbiting a star.

Example: Our solar system orbits the Sun.

So, Star odd one out. Star is the only single celestial object. All others are groups or systems made of stars or celestial bodies.

Thus, correct option is (c).