Match the columns.

Column-$I$	Column-$II$
$(a)$ Splicing	$(1)$ Lac Operon
$(b)$ Okazaki fragments	$(2)$ Lagging strands
$(c)$ Jacob and Monod	$(3)$ Lactose
$(d)$ Inducer	$(4)$ Removal of introns

$(A)$ The correct matches are as follows:
$(a)$ Splicing refers to the process of removing introns and joining exons in pre-mRNA, which corresponds to $(4)$.
$(b)$ Okazaki fragments are short $DNA$ sequences synthesized discontinuously on the lagging strand during $DNA$ replication, which corresponds to $(2)$.
$(c)$ Jacob and Monod were the scientists who proposed the operon model, specifically the Lac Operon, which corresponds to $(1)$.
$(d)$ An inducer is a molecule that regulates gene expression by binding to a repressor protein; in the Lac Operon, lactose acts as the inducer, which corresponds to $(3)$.
Therefore, the correct matching is $(a-4, b-2, c-1, d-3)$.