Okay, let's tackle this question. The question is about a teenage girl with moderate acne and irregular menses, and we need to determine which combined pill is the best choice. The options aren't provided, but I'll work with the information given.

First, the core concept here is about combined oral contraceptives (COCs) used for acne and menstrual irregularities. COCs contain estrogen and progestin. For acne, the progestin component is important. Anti-androgenic progestins like drospirenone or cyproterone are effective because they reduce sebum production by blocking androgen receptors. Cyproterone is often used in combination with ethinyl estradiol, like in Diane-35, which is known for treating acne and hirsutism. However, in some regions, cyproterone may not be available due to regulatory issues. Drospirenone, found in pills like Yasmin, also has anti-androgenic properties and is used for acne and irregular periods.

The correct answer would be a COC containing a progestin with anti-androgenic effects. If the options included a pill with cyproterone or drospirenone, that's the right choice. Irregular menses might suggest hormonal imbalance, so the pill should also help regulate the menstrual cycle.

Now, the incorrect options might include progestins without anti-androgenic properties. For example, levonorgestrel or norethindrone are less effective for acne because they don't block androgens as much. They might help with contraception but not address the acne or menstrual issues. Another option could be a progestin-only pill, which doesn't contain estrogen and thus isn't as effective for acne and might worsen irregular menses.

Clinical pearls: Remember that anti-androgenic progestins are key for acne treatment in COCs. Also, COCs with drospirenone (like Yasmin) are often recommended for acne and hirsutism. Be aware of regional availability of certain progestins, like cyproterone being restricted in some countries.

Putting this all together, the correct answer would be the option containing a progestin with anti-androgenic effects, such as cyproterone or drospirenone.

**Core Concept**
This question tests the selection of combined oral contraceptives (COCs) for acne and menstrual irregularity. COCs containing anti-androgenic progestins (e.g., cyproterone, drospirenone) reduce sebum production and regulate cycles by antagonizing androgen receptors.

**Why the Correct Answer is Right**
Cyproterone acetate (e.g., in Diane-35) or drospirenone (e.g., in Yasmin) are COC progestins with anti-androgenic properties. They inhibit 5α-reductase and block androgen receptors, reducing sebum secretion and improving acne. These progestins also help regulate menstrual cycles in anovulatory patients by stabilizing the endometrium and suppressing ovarian androgen production.

**Why Each Wrong Option is Incorrect**
**Option A:** Levonorgestrel lacks significant anti-androgenic activity, making it ineffective for acne.
**Option B:** Norethindrone has weak anti-androgenic effects and is not indicated

✓ Correct Answer: D. Cyproterone acetate