A major study of the effectiveness of the PSA $($Payment for Environmental Services$)$ program in Costa Rica determined that

A$)$ the program was extremely effective, and deforestation rates began to decline as soon as the program was instituted

B$)$ the program was initiated too late for the forests of Costa Rica to recover

C$)$ deforestation rates began to decline as an immediate result of the program, but farmers quickly removed their land from the program and reverted to their prior deforestation practices once they were paid

D$)$ deforestation rates had already been dropping before the program was started

E$)$ the program was counterproductive because deforestation continued unchecked even after landowners signed up for the program