Step 1: Concept Assessment: This question evaluates understanding of pipeline transportation's applications and constraints.
Step 2: Detailed Analysis: Evaluating each statement:
(A) Pipelines are extensively used to transport liquid and gases. This statement is accurate. The principal application of pipelines is the long-distance conveyance of crude oil, refined petroleum products, natural gas, and water.
(B) Pipelines can also be used to transport liquified coal. This statement is accurate. Coal can be pulverized into a fine powder, mixed with water to form a "slurry," and then transported via pipelines.
(C) Milk is not supplied through pipelines in any country of the world as it is unhealthy. This statement is inaccurate. In certain dairy-producing regions (e.g., New Zealand, parts of Europe), pipelines are utilized to transport milk from milking facilities to centralized processing plants. The assertion of it being "unhealthy" is false, as proper sanitation protocols are maintained.
(D) LPG is supplied only through gas cylinders for safety reasons. This statement is inaccurate. Although cylinders are a common delivery method, numerous urban areas are equipped with piped gas networks that supply LPG or natural gas directly to residences.
Therefore, only statements (A) and (B) are correct.
Step 3: Conclusion: The correct option is the one encompassing exclusively statements (A) and (B).