Answer: Option (d) is the correct answer.
Explanation:
When a substance is absorbed on another substance then this process is known as absorption.
For example, when NaOH is felt on the arm of Howard then absorption of chemical takes place on his skin due to which he has a burn mark.
Inhalation is defined as a process of breathing in something. Ingestion is a process of swallowing or eating food.
And, injection is a process of taking a medicine using a syringe and a needle.
Thus, we can conclude that the given chemical route of entry is absorption.
