If there are N firms in the economy, each assigned with a serial number from 1 to N, then as per the product method, GDP can be written as ______.

GVA1 – GVA2 ..... – GVAN NVA1 + NVA2 ..... + NVAN GVA1 + GVA2 ..... + GVAN GVA1 + NVA2 + GVA3 + NVA4.........

GVA1 + GVA2 ..... + GVAN