The correct answer is option 4 - Abolition of titles except military and academic. The fundamental duties are mentioned in Article 51A of the Indian Constitution and are a set of moral and civic responsibilities that every citizen should fulfill. Option 1 emphasizes the duty to abide by the constitution and respect the National Flag, which is indeed a fundamental duty. Option 2 highlights the duty to promote harmony and brotherhood, which is also a fundamental duty. Option 3 stresses the duty to uphold and protect the sovereignty of the country, which is another fundamental duty. However, option 4, the abolition of titles except military and academic, is not mentioned as a fundamental duty in the Constitution. It is important for citizens to be aware of their fundamental duties and strive to fulfill them for the betterment of society.