Correct Answer: C

Rationale: Tim's physical characteristics, such as narrow shoulders, low muscle mass, and lack of facial and body hair, are typical signs of Klinefelter syndrome, a genetic condition where males have an extra X chromosome (XXY). This leads to underdeveloped testes and reduced testosterone production, resulting in features like gynecomastia, sparse facial and body hair, and reduced muscle mass. Testosterone replacement therapy is commonly used to address the hormonal imbalance in individuals with Klinefelter syndrome. Phenylketonuria (PKU) is a metabolic disorder unrelated to the symptoms described in Tim's case. Cystic fibrosis is a genetic respiratory condition that does not present with the physical characteristics mentioned. Huntington's disease (HD) is a neurodegenerative disorder primarily affecting motor function and cognition, not physical appearance and muscle mass.

Correct Answer: D

Rationale: The correct answer is D. Cervical changes such as effacement and dilation to 2 cm are strong indicators of imminent preterm labor. These changes, combined with regular contractions, can signify labor at any gestation. Estriol can be detected in maternal plasma as early as 9 weeks of gestation. Levels of salivary estriol have been linked to preterm birth. Irregular, mild contractions occurring every 12 to 15 minutes without cervical change are generally not concerning. While the presence of fetal fibronectin in vaginal secretions between 24 and 36 weeks of gestation may predict preterm labor, its predictive value is limited (20%-40%). Therefore, cervical changes provide more reliable information regarding the risk of preterm labor.

Correct Answer: C

Rationale: Uterine atony is the most likely cause of bleeding 4 hours after delivery, especially after delivering a macrosomic infant and augmenting labor with oxytocin. Uterine atony is characterized by the inability of the uterine muscles to contract effectively after childbirth, leading to excessive bleeding. The other options, such as retained placental fragments (A), unrepaired vaginal lacerations (B), and puerperal infection (D), are less likely causes of postpartum hemorrhage in this scenario. Retained placental fragments can cause bleeding, but this typically presents earlier than 4 hours postpartum. Unrepaired vaginal lacerations would likely be evident sooner and not typically result in significant bleeding. Puerperal infection is not a common cause of immediate postpartum hemorrhage unless there are other signs of infection present.

Correct Answer: C

Rationale: The correct answer is C: Herpes Simplex Virus (HSV). HSV can present with small vesicles on the genital area, and it is a concern during labor due to the risk of transmission to the newborn. Genital warts (Choice A) are caused by the human papillomavirus (HPV) and typically present as flesh-colored growths, not vesicles. Syphilis (Choice B) manifests as painless sores and can have systemic effects but does not typically present with vesicles. German measles (Choice D), also known as Rubella, is a viral illness characterized by a red rash, fever, and lymphadenopathy, not vesicles.

Correct Answer: A

Rationale: The correct answer is A: Cytosine with guanine. In the DNA double helix, cytosine always pairs with guanine forming a base pair, and adenine pairs with thymine. These complementary base pairs form the rungs of the ladder-like structure of DNA. Choice B, Rhodamine with biotin, is incorrect as they are not base pairs found in DNA. Choice D, Serine with tyrosine, is incorrect as they are amino acids, not DNA bases. Choice C, Diaminopurine with ribozyme, is also incorrect as ribozyme is an enzyme, not a base, and diaminopurine is not one of the standard bases found in DNA.