Option 1 states that the words "Socialist" and "Secular" were not originally part of the Constitution of India. This statement is generally correct. The original Constitution of India did not explicitly mention the words "Socialist" and "Secular." However, through judicial interpretation, these ideals have been recognized as inherent in the constitution.

Option 2 correctly mentions that the Preamble of the Constitution of India states the objects and aspirations of the constitution. The Preamble outlines the goals of justice, liberty, equality, and fraternity amongst the people of India.

Option 3 states that the Preamble is enforceable in a Court of Law. This statement is incorrect. The Preamble is not enforceable in a court of law as it is not legally binding. However, the Supreme Court has held that the Preamble can be used as a guiding principle while interpreting the Constitution.

Option 4 correctly states that a Republic refers to the people as the source of all authority under the Constitution. In a Republic, the political power resides with the citizens, who elect representatives to govern on their behalf.

In summary, the incorrect statement is option 3, as the Preamble is not enforceable in a court of law.