Okay, let's tackle this question about Kartagener's syndrome. The question is asking which of the options are true. The options given are dextrocardia, infertility, mental retardation, and bronchiectasis. The correct answer is supposed to be all except one, but I need to figure out which ones are correct.

First, I remember that Kartagener's syndrome is a subset of primary ciliary dyskinesia. The main features are situs inversus (which includes dextrocardia), chronic sinusitis, bronchiectasis, and infertility. Mental retardation isn't part of it. So let me break it down.

Dextrocardia (option a) is when the heart is on the right side. Since Kartagener's is associated with situs inversus, that makes sense. So a is correct.

Infertility (option b) is another key feature. In males, it's due to immotile sperm, which is part of the ciliary dysfunction. So b is correct.

Mental retardation (option c) isn't related. Kartagener's doesn't affect cognitive function. So c is the incorrect option here.

Bronchiectasis (option d) is a common complication because of the impaired mucociliary clearance leading to chronic infections. So d is correct.

So the correct answer should be options a, b, d. But the question is structured as a multiple-choice question with options a to d. The user's correct answer is likely all except c. So the answer is A, B, D. But the options given are separate. Wait, the user's correct answer is not specified here, but in the original question, the correct answer is probably all except C. So the correct answer would be A, B, D. But the way the options are presented in the question isn't clear if it's a single answer or multiple. Wait, the original question says "True about Kartagener's syndrome" and gives four options. The correct answer is probably all except C, so the correct options are A, B, D. But since the user's correct answer is to be filled in, I need to check the standard answer for Kartagener's syndrome.

Yes, the classic triad is situs inversus (dextrocardia), bronchiectasis, and infertility. Mental retardation is not part of it. So the correct answer is A, B, D. Therefore, the correct options are A, B, D. The options given are a to d, so the correct answer would be all except C. So the correct answer is A, B, D. But the way the user presented the options is A-D as options. Wait, the original question's options are a, b, c, d, and the correct answer is which ones are true. The correct answer would be all except C. So the answer is A, B, D. But in the user's setup, the correct answer is to be written as, for example, "Correct Answer: A. Dextrocardia" but since multiple are correct, perhaps the question is a multiple true/false question. However, the user's setup shows four options with a single correct answer. Wait, the user's original question is structured as a multiple-choice question with options a to d, and the correct answer is supposed to be selected. However

✓ Correct Answer: B. abd