It is the science of measuring components (cells) and properties of individual cells in liquid suspension—

Correct option is A

Option (a): Correct
• Flow cytometry is a technique that analyzes individual cells in a liquid stream.
• It measures size, granularity, surface markers, fluorescence, and other properties.
• It is widely used in microbiology, immunology, toxicology, and food safety labs for cell counting and characterization.
Option (b): Incorrect
• Fibre optics is related to light transmission for communication, not cell measurement.
Option (c): Incorrect
• Ribotyping is a genetic fingerprinting method involving rRNA genes, not single-cell measurement.
Option (d): Incorrect
• PCR amplifies DNA but does not analyze whole cells in suspension.