Correct Answer - Option 2 : Polymer bonding agents
Retarders: Retarders for concrete are used to delay the initial setting time of the concrete up to an extent. They are generally used in the hot weather condition to counter the rapid hardening due to high temperature, thus allowing them time for mixing, transporting, and placing.
Plasticizers: The combination of organic substances or combinations of organic and inorganic substances that cause a reduction in water content for given workability or give higher workability at the same water content are known or termed as plasticizer admixtures.
Grouting Admixtures: Portland cement grouts are used for a variety of purposes to stabilize foundations, set machine bases, fill cracks and joints in concrete work, cement oil wells, fill cores of masonry walls, grout prestressing tendons and anchor bolts, and fill the voids in preplaced aggregate concrete.
Polymer Bonding Agents: Polymer Bonding Agent is an aqueous emulsion of a polymer and chemical admixtures. It is designed for use as a bonding agent with concrete and cement-based products in interior or exterior applications. It doesn't affect any specific properties of concrete.