In India, the term "Public Key Infrastructure" is used in the context of

Answer: A. PUBLIC KEY INFRASTRUCTURE (PKI) is used in the context of DIGITAL SECURITY INFRASTRUCTURE. PUBLIC KEY INFRASTRUCTURE (PKI) is the system of CRYPTOGRAPHIC PROTOCOLS, ROLES, POLICIES, HARDWARE, SOFTWARE AND PROCEDURES needed to create, manage, distribute, use, store and revoke DIGITAL CERTIFICATES and to manage PUBLIC-KEY ENCRYPTION. PKI is the foundation of modern digital security, enabling identity verification, authentication, secure communication, and digital signatures. KEY COMPONENTS OF PKI: 1. CERTIFICATE AUTHORITY (CA): a trusted entity that issues digital certificates binding public keys to identities. In India, licensed CAs operate under the CONTROLLER OF CERTIFYING AUTHORITIES (CCA), Ministry of Electronics and Information Technology (MeitY), under the IT Act 2000. 2. REGISTRATION AUTHORITY (RA): verifies the identity of certificate applicants before the CA issues a certificate. 3. DIGITAL CERTIFICATES: contain a public key, the identity of the holder, the CA's signature, and validity period (typically X.509 format). 4. PUBLIC AND PRIVATE KEY PAIRS: paired cryptographic keys; the public key is shared, the private key is kept secret. Anything encrypted with the public key can only be decrypted by the corresponding private key (and vice versa for signatures). USES OF PKI in India: 1. AADHAAR e-KYC, e-SIGN service. 2. DIGITAL SIGNATURES for income tax filings, GST returns, MCA filings, e-procurement. 3. SECURE WEBSITES (HTTPS / TLS). 4. EMAIL SECURITY (S/MIME). 5. BLOCKCHAIN AND DIGITAL CURRENCY systems. 6. CODE SIGNING for software distribution. India's IT Act 2000 (Sections 35 to 39) provides the legal framework for digital signatures and the PKI ecosystem. Recognised CAs in India include eMudhra, Sify, NIC, IDRBT. Why other options are WRONG: (B) Food security in India is delivered through PDS, NFSA 2013, FCI procurement, ICDS, etc. Not 'Public Key Infrastructure'. (C) Healthcare and education infrastructure encompasses hospitals, schools, sub-centres etc. PKI is not its name. (D) Telecommunication and transport infrastructure is built by DoT, TRAI, NHAI, IR. PKI is a cryptographic concept, not transport. Source: IT Act 2000 (Sections 35-39); CCA India website; ITU and NIST PKI standards documentation.