lookup(String, Any, Number)
This function enables you to execute a flow within a Mule app and retrieve the resulting payload.
It works in Mule apps that are running on Mule Runtime version 4.1.4 and later.
Similar to the Flow Reference component (recommended), the lookup function enables you to execute another flow within your app and to retrieve the resulting payload. It takes the flow's name and an input payload as parameters. For example, lookup("anotherFlow", payload) executes a flow named anotherFlow.
Correct answer is
lookup( "createCustomerObject", {first: "Aice, last: "Green"})
MuleSoft Documentation Reference : https://docs.mulesoft.com/mule-runtime/4.3/dw-mule-functions-lookup