What is the next step in the process after a substrate enters the active site of an enzyme?

Enzymes are biocatalysts which increases the rate of the biochemical reaction by lowering the activation energy of the reaction.

It performs the catalysis in four steps:

The substrate enters the active site of a specific enzyme. The specificity is determined by shape complementarity and non-covalent interactions such as hydrophobic interactions. These interactions bring some changes in the shape of the active site of the enzyme which results in the formation of the enzyme-substrate complex. The process of catalysis takes place by which the substrate is converted into the product. It includes the breaking or rearrangement of old bonds and formation of new bonds. It results in the formation of enzyme-product complex. The product has different properties as compared to the substrate due to which it gets released from the active site of the enzyme. The free enzyme is ready to initiate a new cycle.

Thus, the correct answer would be the formation of the enzyme-substrate complex.