Step 1: Find the economic order quantity using the EOQ formula.
With demand \( D = 100 \) units/day, ordering cost \( C_o = Rs.\,400 \) per order and holding cost \( C_h = Rs.\,0.08 \) per unit per day, the economic lot size is
\[ Q^* = \sqrt{\frac{2DC_o}{C_h}} = \sqrt{\frac{2 \times 100 \times 400}{0.08}} = \sqrt{1{,}000{,}000} = 1000 \text{ units} \]
Step 2: Work out how long one order cycle lasts.
An order of 1000 units at a consumption rate of 100 units per day lasts
\[ t_c = \frac{Q^*}{D} = \frac{1000}{100} = 10 \text{ days} \]
so a fresh batch of 1000 units is consumed in exactly 10 days.
Step 3: Locate the reorder point within the lead time.
The lead time is 13 days, which is one full 10 day cycle plus 3 extra days. So when the order is placed, stock only needs to cover those leftover 3 days of demand before the fresh batch lands, giving
\[ \text{ROP} = 3 \times 100 = \boxed{300 \text{ units}} \]
Together with \( Q^* = 1000 \) units, this matches option 4.