The Preamble of a constitution is a brief introductory statement that sets out the guiding principles and goals of the constitution. It serves as a useful tool in constitutional interpretation because it provides insights into the underlying objectives and philosophy of the constitution makers.

Option 1 suggests that the Preamble uses value-loaded words. While it is true that the Preamble often uses words like "justice", "equality", and "liberty", these words are meant to reflect the core values and principles that the constitution is based on, rather than being value-loaded.

Option 3 states that the Preamble is a source of power and limitation. While the Preamble does outline the broad objectives and aspirations of the constitution, it is not a direct source of power or limitation. Instead, it provides an overarching framework within which the constitution operates.

Option 4 claims that the Preamble gives an exhaustive list of basic features of the Constitution. This is not accurate as the Preamble only provides a broad overview of the goals and objectives of the constitution, rather than an exhaustive list of specific features.

Therefore, option 2 is the correct answer as it correctly identifies that the Preamble contains the real objective and philosophy of the Constitution makers, making it a valuable tool in constitutional interpretation.