Final answer:
The economy experienced an expansion from May 1954 to April 1957 based on the provided data.
Step-by-step explanation:
The question is asking about the period of economic expansion in the U.S. based on the provided data. In order to determine the correct answer, we need to identify the dates where the economy experienced a turning point from a recession to an expansion. From the given data, the economy experienced a turning point in May 1954 and another in April 1957. Therefore, the correct answer is option C. May 1954 to April 1957.