MRP - When to order

Company produces the product A101 with demand 10 units per day. It uses three raw materials C301, C302 and C303. From these raw materials, the company produces B201 and B202 that are used in the production of the final product.

Inventory record (in the beginning of day 1):

Bill of materials:

A101 is made of 1 x B201 + 3 x B202

B201 is made of 3 x C301 + 1 x C302

B202 is made of 2 x C302 + 2 x C303

C301, C302 and C303 are raw materials that are purchased from a supplier.

When should C302 be ordered?

After 6 days

After 12 days

After 18 days

After 26 days

\begin{tabular}{|l|l|l|l|l|l|l|} \hline & A101 & B201 & B202 & C301 & C302 & C303 \\ \hline Units on stock & 310 & 920 & 1020 & 2280 & 1531 & 5922 \\ \hline EOQ/EBQ(units) & 480 & 1600 & 2500 & 3000 & 9000 & 20000 \\ \hline Leadtime(days) & 1 & 3 & 2 & 9 & 2 & 5 \\ \hline \end{tabular}