**Core Concept**
DMPA (Depot Medroxyprogesterone Acetate) is a long-acting reversible contraceptive injection that works by releasing a steady amount of progestin into the bloodstream, thereby preventing ovulation. It is administered every 12 weeks (3 months) to maintain contraceptive efficacy.

**Why the Correct Answer is Right**
The correct administration interval of DMPA is 3 months, as it takes this long for the depot formulation to release the active ingredient into the bloodstream. This prolonged release of progestin suppresses the luteinizing hormone surge, preventing ovulation and subsequent fertilization. The injection is given deep into the gluteal muscle, where it forms a depot that slowly releases the hormone.

**Why Each Wrong Option is Incorrect**
**Option A:** This is too short of an interval and would result in inadequate contraceptive coverage, increasing the risk of unintended pregnancy.
**Option B:** This option is too long and would likely lead to loss of contraceptive efficacy, as the depot formulation would have fully released its active ingredient.
**Option C:** This option is not a valid administration interval for DMPA and is likely a distractor.

**Clinical Pearl / High-Yield Fact**
It's essential to note that DMPA is a highly effective contraceptive method, with a failure rate of less than 1%. However, it may cause irregular bleeding or amenorrhea in some users, which can be a significant drawback.

**Correct Answer:** D. 12 weeks