He hated getting shots and cringed in anticipation of the moment when the doctor’s syringe would _________ his arm and bring pain.invokeinundatepenetratevacate

The best word to complete the sentence is "penetrate."

The full sentence would read: "He hated getting shots and cringed in anticipation of the moment when the doctor’s syringe would penetrate his arm and bring pain."

Here's a brief explanation of why "penetrate" is the most appropriate choice:

• Invoke means to call upon something, often a memory or feeling, and does not fit the context of a syringe.
• Inundate means to overwhelm, typically with a flood of something, which is not relevant here.
• Vacate means to leave or empty a place, which does not apply to the context of a shot being administered.

"Penetrate" accurately describes the action of the syringe entering the skin, aligning perfectly with the anticipation of pain.