Detailed Analysis of Electric Fuse Properties:

• Low Melting Point (Statement A): The fuse element must melt safely and rapidly during overcurrent faults (e.g., tin-lead alloy, copper, silver). (True).
• High Conductivity (Statement B): To minimize normal power loss ($I^2 R$) and voltage drop under rated working conditions. (True).
• Inverse Time-Current Characteristics (Statement C): The higher the fault current, the shorter the time required for the fuse element to melt and clear the circuit ($t \propto 1/I^2$). (True).
• Inserted in Series (Statement D): Must be wired in series with the phase/live conductor so that melting breaks the fault circuit entirely. (True).
  All four statements (A), (B), (C), and (D) are true. Hence, Option 4 is correct.

Statement (I) is true: DC produces no time-varying magnetic field inside the conductor, so current density is completely uniform across the cross-section. Statement (II) is true: AC produces time-varying internal magnetic flux causing skin effect, concentrating current near the outer periphery. Option analysis: (A) Both Statement (I) and Statement (II) are true. (B) Both are false is incorrect. (C) Statement (II) is true. (D) Statement (I) is true.

High-voltage overhead electric power transmission universally employs the $3$-phase, $3$-wire system because balanced $3$-phase transmission requires no neutral conductor, drastically saving copper/aluminium conductor costs. (Distribution uses $3$-phase, $4$-wire). Option analysis: (A) $3$-phase, $3$-wire is the universal power transmission system in India. (B) $1$-phase, $3$-wire is obsolete/distribution only. (C) $1$-phase, $1$-wire is not a standard AC transmission system. (D) $3$-phase cannot be transmitted on a single wire.