Help please i do not get this

I’m stuck on this equation, anyone got the answer?

Find the rate at which the water is now flowing from the tap give your answer cubic centimetres per second

Tom and lilly rented a house for $12,000 last year. at the start of the year they bought the house they had been renting directly from the owner for $250,000. they believe they could rent it for $12,000 this year, but stay in the house. how much does tom and lilly’s decision to buy the house change gdp? a. it reduces gdp by $12,000 b. it does not change gdp c. it raises gdp by $238,000 d. it raises gdp by $250,000