A) The adjective in the sentence is expensive*.

Here are the answers to question 7:

*a) The adjective in the sentence is expensive.

*b) My car needs repairing right now.

*c) This is the house where we spent our childhood.
(Alternatively: This is the house in which we spent our childhood.)

*d) Sumsher along with his friends knows me well.

*e) Don't stare at me. I have no mistake.

*f) You must not tell anyone about this. It's too confidential.

*g) The customer had purchased the machine before he complained about the error.

*h) Despite being close friends, we have not seen each other's houses.

*i) Yangma said that I was her source of inspiration in life.

*j) His project was being presented by Loku for the first time.