听力原文： The governors of 45 states agreed Sunday to develop common measures for establis

hing high school graduation rates, a step they said will help achieve their larger goal of making high school rigorous enough to help prepare students for an increasingly competitive global economy.

The agreement aims to replace a hodgepodge of measuring systems with a uniform. standard that will allow parents, students, educators and politicians to compare state graduation rates. Virginia Gov. Mark R. Warner(D) , the outgoing chairman of the National Governors Association, said that with uniform. data on graduation rates and eventually dropout rates, states will have tools to help them track and target efforts to push all students to graduate from high school.

Education experts say a key predictor of whether students eventually will graduate from college is not race or economic circumstances but whether they completed a rigorous course of study in high school. Warner has used his year as NGA chairman to spearhead the initiative to raise awareness of the weaknesses of U. S. high schools and establish higher standards and more difficult curricula.

Governors reiterated Sunday their belief that global competitiveness has left U.S. students in a precarious position, with an economy that demands greater skills but a high school system still designed for the old economy.

What is the main topic of this news？

A．A uniform. standard on graduation rates.

B．A global economy.

C．The reform. of the current high school system.

D．The National Governors Association.