Concept:The s-block consists of elements whose outermost electrons enter the s-orbital.Explanation:In the periodic table, the s-block is located on the far left.It contains only elements from Group 1 and Group 2.Group 1 includes alkali metals, and Group 2 includes alkaline earth metals.Groups 3 to 7 belong to the d-block and p-block, not the s-block.Therefore, the s-block is made up of only groups 1 and 2.Answer:B. groups 1, and 2