Answer :
Final answer:
The sample of concrete for the slump test must be obtained in accordance with ASTM Standard C143.
Explanation:
The correct answer is a) C143. The sample of concrete for the slump test is obtained in accordance with ASTM Standard C143. ASTM stands for the American Society for Testing and Materials, which is an international standards organization that develops and publishes technical standards for various materials, including concrete. Standard C143 specifically provides guidelines for obtaining and testing samples of freshly mixed concrete to determine its consistency or workability.