Final answer:
The most indicative behavior of abuse in a toddler with a dislocated shoulder and a simple fracture is not crying when moved, suggesting an atypical response to pain or a disorganized attachment style possibly due to abuse. Non-accidental trauma should be considered, especially without a clear accidental cause.
Step-by-step explanation:
The behavior that most strongly suggests a child's injuries stem from abuse is number 4, Not crying when moved. It's unusual for a toddler with a dislocated shoulder and a simple fracture of the right humerus not to cry due to the pain when being moved. Considering the research showing that abuse disrupts a child's ability to regulate their emotions, a lack of crying could indicate that the child has experienced abuse and may have developed an atypical response to pain or a disorganized attachment style.
Injuries such as a dislocated shoulder or a humerus fracture can happen due to falls or accidents, often involving a significant force such as landing on an outstretched arm. However, in the absence of a credible accident report, these injuries, especially in combination and in a non-mobile toddler, could be suggestive of non-accidental trauma.
Moreover, given that a toddler's cry is often a trigger for shaking or other violent actions, it's important that healthcare professionals consider the possibility of shaken-baby syndrome or other forms of abuse when encountering such injuries without a clear accidental cause.