A nurse is teaching adolescent boys about pubertal changes. The first sign of pubertal change seen with boys is

Intussusception is a medical condition where a portion of the intestine telescopes into an adjacent section, causing an obstruction. This obstruction can affect the normal passage of stool through the intestine.

In intussusception, the obstructed intestine can lead to the development of blood and mucus within the stool, giving it a characteristic appearance described as "currant jelly." The stool may contain a combination of blood, mucus, and faecal matter, resembling the colour and consistency of currant jelly.

loose, foul-smelling stools in (option) is incorrect because it, is not specific to intussusception and can be associated with various gastrointestinal conditions.

hard stools positive for guaiac in (option C) is incorrect because it, is not typical of intussusception. Hard stools and positive guaiac test results are more commonly associated with constipation or other conditions affecting the lower gastrointestinal tract.

ribbon-like stools, in (option D) is incorrect because it may be seen in conditions like colorectal cancer or other obstructive disorders. However, it is not a specific characteristic of intussusception.

In the context of intussusception, the presence of "currant jelly" stools is considered a significant sign and should prompt immediate medical attention. Intussusception is a medical emergency and requires prompt diagnosis and treatment.

Upper extremity fractures in children commonly occur as a result of falls. Children are more prone to falls due to their developing motor skills, balance, and coordination. They may fall from playground equipment, bicycles, or simply while running or playing.

While sports injuries (Option A) can also lead to upper extremity fractures, falls are generally the most common cause in children.

Physical abuse (Option B) is an unfortunate possibility in some cases, but it is important to approach the assessment without assuming abuse as the cause without appropriate evidence or disclosure.

Upper extremity fractures resulting from automobile crashes (Option D) are less common in children compared to falls or sports injuries, although they can occur in severe accidents.

It is always important for the nurse to assess the child's history, obtain a detailed account of the injury, and consider any additional signs or indications that may suggest non-accidental trauma if appropriate.