Select the correct one-word substitution for the highlighted phrase.
After my father passed away, I used to look at a series of stars, trying to find the unknown.

Correct option is D

The correct one-word for the given group of words is (d) Constellation.
A constellation is a group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure. (तारों का समूह)
Example: The constellation Orion is visible in the winter night sky.
Meanings of the given other options:
· (a) Caravan: A group of people, especially traders or pilgrims, traveling together across a desert. (यात्रियों का समूह)
· (b) Galaxy: A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction. (आकाशगंगा)
· (c) Horde: A large group of people. (भीड़)