Correct : a

The correct answer is Option A — Rs. 0.
To find the total profit, we calculate the number of shares purchased, the selling value, and the net gain or loss for each stock separately, then combine them.
Stock A: The investor buys at Rs. 50 per share and invests Rs. 100, acquiring 100 ÷ 50 = 2 shares. The next day, Stock A is worth Rs. 55 per share, so the selling value is 2 × 55 = Rs. 110. Profit from Stock A = Rs. 110 − Rs. 100 = +Rs. 10.
Stock B: The investor buys at Rs. 80 per share and invests Rs. 80, acquiring 80 ÷ 80 = 1 share. The next day, Stock B falls to Rs. 70 per share, so the selling value is 1 × 70 = Rs. 70. Loss from Stock B = Rs. 70 − Rs. 80 = −Rs. 10.
Total profit = (+Rs. 10) + (−Rs. 10) = Rs. 0.
The gain on Stock A is exactly cancelled out by the loss on Stock B, leaving the investor with zero net profit. The total amount invested was Rs. 180 (100 + 80) and the total selling value is also Rs. 180 (110 + 70), confirming the answer.