**Core Concept**
Dalrymple's sign is a clinical feature associated with **ocular Graves' disease**, which is an autoimmune condition leading to **thyrotoxicosis** and **exophthalmos**. This sign is related to the retraction of the upper eyelid.

**Why the Correct Answer is Right**
The correct answer refers to the retraction of the upper eyelid, which is a characteristic feature of Dalrymple's sign. This occurs due to the increased sympathetic activity and **inflammation of the orbital tissues**, leading to **eyelid retraction**.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe Dalrymple's sign.
**Option B:** Similarly, this option is incorrect and does not relate to the definition of Dalrymple's sign.
**Option D:** This option is also incorrect as Dalrymple's sign is specifically related to eyelid retraction, not other symptoms.

**Clinical Pearl / High-Yield Fact**
Dalrymple's sign is an important clinical feature to recognize, as it can be an early indicator of **ocular Graves' disease**. It is often seen in conjunction with other signs such as **von Graefe's sign** and **Möbius sign**.

**Correct Answer:** D. Retraction of the upper eyelid.