This process requires an energy input from ——-to occur.

This process requires an energy input from an external source to occur.

To determine the process that requires an energy input, we need to consider what types of processes generally require energy.

1. Chemical reactions: Many chemical reactions require energy to proceed. This energy can come from various sources, such as heat, electricity, or light.

2. Physical changes: Some physical changes, such as phase changes (e.g., melting, boiling), also require an energy input. Heat is often the source of energy in these cases.

3. Biological processes: Various biological processes, such as muscle contraction or nutrient absorption in cellular respiration, require energy in the form of ATP (adenosine triphosphate).

Based on the given information, it's difficult to pinpoint the specific process mentioned, but knowing the general types of processes that require energy should help in understanding how to identify the correct one.

To determine the specific energy input required for a process to occur, the context and nature of the process need to be specified. Different processes have different energy requirements, and it is important to understand what kind of energy input is being referred to. Please provide more information about the process in question, and I'll be happy to assist you further.