Select the most appropriate one word substitution for the given group of words.

To increase the speed

Accelerate

The most appropriate one-word substitution for the given group of words "to increase the speed" is accelerate.

• Accelerate means to increase the speed of something.
• Activate means to make something start working or operating.
• Exhilarate means to make someone feel very happy and excited.
• Assimilate means to absorb or incorporate something into something else.

The word accelerate is the most appropriate because it specifically refers to increasing the speed of something. The other words do not have the same connotation of speed.