What is the count of genes that determine the synthesis of one enzyme?

The correct option is One.

This concept is fundamentally explained by the classical genetic hypothesis known as the "one gene-one enzyme hypothesis" proposed by geneticists George Beadle and Edward Tatum in 1941. Through their research on the red bread mold Neurospora crassa, they demonstrated a direct relationship between genes and biochemical reactions.

Their findings showed that:
1. Each gene in an organism's DNA contains the specific genetic code or instructions to synthesize a single polypeptide or protein.
2. Enzymes, which act as biological catalysts for chemical reactions in cells, are proteins.
3. Therefore, the synthesis of one specific enzyme is controlled and determined by one specific gene.

While modern molecular biology has updated this to the "one gene-one polypeptide" hypothesis (since some enzymes and proteins consist of multiple polypeptide chains encoded by different genes, and alternative splicing can produce multiple proteins from a single gene), the classical answer to the count of genes determining the synthesis of a single enzyme is one.