Okay, let's tackle this question. The question is about when the weight of the placenta and fetus are equal. I remember that during pregnancy, the placenta grows along with the fetus. But when exactly do their weights match?

First, I need to recall the timeline of pregnancy. Gestation is 40 weeks, right? Early on, the placenta is probably smaller, but as the fetus develops, the placenta's size increases. But there's a point where they become equal. I think it's in the second trimester. Maybe around 16-20 weeks? Wait, I've heard that the placenta reaches maximum weight around the third trimester, but when does it equal the fetus?

Wait, let me think. The placenta's weight increases throughout pregnancy. At term, the placenta is about 500 grams, and the fetus is around 3000 grams. So maybe they cross somewhere in the middle. If the placenta is 500g at term, then maybe halfway through pregnancy, the fetus is 500g. That would be around 20 weeks? Because at 20 weeks, the fetus is about 300 grams, and the placenta might be similar. But I need to check the exact timing.

Another angle: the placenta's weight is about 20% of the fetus's weight at term. So if the fetus is 3kg, placenta is 600g. But when are they equal? Let's do the math. If the fetus is growing exponentially and the placenta is growing linearly, there's a point where they cross. Maybe around 12-16 weeks? Or maybe 24 weeks?

Wait, I think the correct answer is 20 weeks. Because by 20 weeks, the fetus is around 300 grams, and the placenta would be similar in weight. But I need to confirm. Some sources say that the placenta and fetus are equal in weight at about 20 weeks. That's a high-yield point. So the answer is 20 weeks. Let me check the options again. The options are A, B, C, D but the question didn't list them. Oh, the user provided the question with options but they are empty. So the correct answer is 20 weeks. So the correct answer letter would be whatever option corresponds to 20 weeks. Since the user didn't list options, maybe the original question had options like 12 weeks, 16 weeks, 20 weeks, 24 weeks. So the correct answer is 20 weeks. Therefore, the explanation should focus on that.

**Core Concept**
The question tests understanding of fetal and placental growth dynamics during gestation. The placenta and fetus grow at different rates, with their weights intersecting at a specific gestational age. This is a high-yield topic for obstetrics and fetal development.

**Why the Correct Answer is Right**
At approximately **20 weeks of gestation**, the placenta and fetus reach equal weight (~300 grams). Before this, the fetus grows faster; after this, placental growth slows while fetal growth accelerates. This intersection occurs because placental weight plateaus around 20 weeks, while the fetus continues exponential growth until term.

✓ Correct Answer: C. 17 weeks