**Core Concept**
The underlying principle being tested is the relationship between thyroid-stimulating hormone (TSH) levels and hypothyroidism, which is characterized by low levels of thyroid hormones (**T3** and **T4**). Hypothyroidism can be primary or secondary, with different effects on TSH levels.

**Why the Correct Answer is Right**
Primary hypothyroidism is associated with an increase in TSH levels as the pituitary gland tries to stimulate the thyroid gland to produce more thyroid hormones. This is a feedback mechanism to compensate for the low levels of **T3** and **T4**.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided, but typically, primary hypothyroidism due to thyroid gland dysfunction (e.g., **Hashimoto's thyroiditis**) would increase TSH.
**Option B:** Similarly, not provided, but conditions like **thyroidectomy** or **radioiodine therapy** leading to primary hypothyroidism would also increase TSH.
**Option C:** And **Option D:** Without specifics, we can say that any cause of primary hypothyroidism would result in elevated TSH, whereas secondary hypothyroidism (due to pituitary or hypothalamic disease) might have low or inappropriately normal TSH levels.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that an elevated TSH level with low **T4** and/or **T3** levels indicates primary hypothyroidism, whereas a low TSH with low **T4** and/or **T3** suggests secondary hypothyroidism.

**Correct Answer:** D. Secondary hypothyroidism