Final answer:
Proteases, hydrolases, oxidoreductases, transferases, and ligases are all recognized as major groups of enzymes by the EC system.
Step-by-step explanation:
The Enzyme Commission (EC) system classifies enzymes into six major groups based on the type of reaction they catalyze. These groups are as follows: (1) Oxidoreductases, (2) Transferases, (3) Hydrolases, (4) Lyases, (5) Isomerases, and (6) Ligases. Therefore, among the options given, proteases, hydrolases, oxidoreductases, transferases, and ligases are all major groups of enzymes recognized by the EC system.
However, proteases are not an EC main group, but they are a type of hydrolase, which is one of the six main groups. As proteases carry out a specific hydrolysis reaction on proteins, they fall under the category of hydrolases (3), making them a subgroup rather than a separate main group recognized by the EC classification system. Lyases is missing from the choices and would be the correct answer since it's one of the six major groups; however, all presented options are indeed recognized enzyme groups.