Explanation:

- Mild: This word describes something gentle, not severe or strong. It can refer to weather, flavors, or temperament.

- Placid (Option 1): Synonymous with calm and peaceful, it is not the opposite of mild. It's a characteristic of tranquil environments or personalities.

- Harsh (Option 2): This means severe, cruel, or unpleasant. It is the correct antonym for mild as it contrasts with something gentle.

- Correct Answer: Harsh

- Bland (Option 3): This is similar to mild, lacking strong flavor or characteristics. It's not an antonym for mild.

- Dented (Option 4): This refers to something that has a hollow or depression. It's unrelated in terms of contrast to mild.