The total mass of the mixture can be calculated by adding the mass of the oil and the mass of the water together.
The mass of the oil is 100 grams, and the mass of the water is 1,000 grams.
So, the total mass is:
100 grams (oil) + 1,000 grams (water) = 1,100 grams.
The correct answer is C. 1,100 grams.