• Bipartite Nature of Gene Regulatory Networks (GRN): GRNs are mathematically modeled as bipartite directed graphs comprising two distinct classes of nodes: regulatory elements (such as transcription factors, small RNAs, and signaling proteins) and target gene loci whose expression is modulated.
• Directionality of Information Flow: Edges connecting nodes possess intrinsic directionality ($A

ightarrow B$), signifying asymmetric regulatory control wherein upstream transcription factors bind specific promoter or enhancer cis-elements to regulate downstream target genes, rather than the reverse.

• Assertion and Reason Verification: Assertion (A) accurately defines GRNs as bipartite and directional networks, and Reason (R) provides the precise mechanistic and topological explanation for why this structural bipartiteness and directionality arise.
• Conclusion: Both (A) and (R) are true and (R) is the correct explanation of (A) (Option 1).

Correct option: (1) Both (A) and (R) are true and (R) is the correct explanation of (A)