Which PHP function is commonly used to load an XML string into a SimpleXMLElement object?

The function commonly used to load an XML string into a SimpleXMLElement object in PHP is loadXML. This function allows you to parse a well-formed XML string and creates a SimpleXMLElement instance, enabling easy manipulation and access to the XML data using an object-oriented interface.

When you use loadXML, the string provided must contain valid XML content, and upon successful parsing, it returns a SimpleXMLElement object that represents the XML structure. This makes it convenient to navigate through the XML's nodes and attributes, providing a straightforward way to work with XML data in PHP.

The other options, while they sound similar, do not represent valid functions in the context of loading XML strings into a SimpleXMLElement object. For example, fromXML, parseXML, and createXML are not standard PHP functions for this purpose, which is why they are not considered correct answers. Therefore, loadXML stands out as the accurate choice in this scenario.