NZ tax law

Which of the following is a taxable activity? Only one is correct

(a) Renting out a small commercial building in Napier for $52,000 per annum.

(b) Renting out a residential house in Ponsonby, Auckland for $62,400 per annum.

(c) Lending $500,000 on a mortgage on a house for $27,000 interest per annum.

(d) Selling a house which you have inherited from your mothers estate for $800,000