The correct spelling is "Conscientious", which means a person wishing to do what is right, especially to do one's work or duty well and thoroughly.

১. Option (ক) misses the "e" after "sci".
২. Option (খ) misses the first "c" after "on".
৩. Option (গ) incorrectly uses "cie" instead of "scie".

অতিরিক্ত তথ্য: Spelling is a frequent topic in BCS English exams to test lexical accuracy.