Answer: Option C
Let C's investment be x. Then, the total investment in the business is given by:A + B + C = 5000 + 8000 + x = 13000 + x
Let the profit earned by the business be P. Then, we can write:Profit earned by A = (25/100) * P
Since the total profit is divided among A, B, and C in the ratio of their investments, we can write:Profit earned by A / A's investment = Profit earned by B / B's investment = Profit earned by C / C's investment
Substituting the given values, we get:(25/100) * P / 5000 = (75/100) * P / 8000 = (P - (25/100) * P - (75/100) * P) / x
Simplifying the above expression, we get:5P / 13000 = P / 3200 = (3/4) * P / x
Solving for x, we get:x = (4/3) * P * (3200/13000) = (16/39) * P
Since A's investment is 5000, we know that A receives 25% of the profit. So, we can write:Profit earned by A = (25/100) * P = (1/4) * P
Substituting this value in the expression for C's investment, we get:x = (16/39) * (1/4) * P = (4/39) * P
Also, we know that A, B, and C have invested a total of 13000 + x in the business. Substituting the value of x, we get:A + B + C = 13000 + x = 13000 + (4/39) * P
Since A and B have invested 5000 and 8000 respectively, we can write:C = 13000 + (4/39) * P - 5000 - 8000 = (4/39) * P - 7000
Hence, the correct option is C (Rs. 7000).
To summarize, we used the following concepts/formulas:

• Ratio and proportion: A comparison of two quantities by division.
• Investment: The amount of money or capital put into a business or project.
• Profit sharing: The distribution of profits among partners or investors in a business.
• Simplification of ratios: Dividing both the numerator and the denominator of a ratio by a common factor to obtain an equivalent ratio.

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