Which virus is complex in structure?

Explanation

The T4 bacteriophage is a complex virus with a highly specialized structure. Its icosahedral head houses double-stranded DNA, while the tail functions like a syringe, using a contractile sheath to inject DNA into the host. The baseplate and long tail fibers help the virus recognize and attach to E. coli, and short spikes pierce the cell wall to enable genome delivery. This intricate design makes T4 much more advanced than simple helical or icosahedral viruses, acting as a molecular machine for efficient infection.