Explanation:

An indelible mark is a mark that cannot be removed or erased. It is permanent and cannot be easily washed away or eliminated. The word "indelible" comes from the Latin word "indelibilis," which means "cannot be deleted."

Indelible:
- Indelible is an adjective that describes something that cannot be removed, erased, or washed away.
- It is used to refer to marks, stains, or impressions that are permanent and cannot be easily eliminated.
- Indelible marks are often made with permanent markers, ink, or dyes that are designed to be long-lasting.

Example:
- If you accidentally spill ink on your clothes, it may leave an indelible mark that cannot be washed away.
- Some tattoos are considered indelible as they are meant to be permanent and cannot be easily removed.

Options:
a) Incredible: This option means something that is hard to believe or astonishing. It does not relate to the concept of a mark that cannot be removed.
b) Invisible: This option means something that cannot be seen or is not visible. It does not relate to the concept of a mark that cannot be removed.
c) Invincible: This option means something that is unbeatable or cannot be defeated. It does not relate to the concept of a mark that cannot be removed.
d) Indelible: This option is the correct answer as it accurately describes a mark that cannot be removed.

Conclusion:
In conclusion, the correct answer is option 'D' - indelible. It is the only option that accurately describes a mark that cannot be removed or erased.