The chemical route to entry in the given scenario will be by absorption. The correct option is d.
A process by which one thing becomes a part of another, or the process by which something soaks, either literally or metaphorically is referred to as absorption.
The missing options are :
As in the given scenario, the solution gets spilled on the arms of Howard and is having a burn mark, which means the solution is absorbed in the skin and is the chemical route of entry.
Thus, the correct option is d.
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