Answer:
d. A perpetuity is a stream of regularly timed, equal cash flows that continues forever.
Explanation:
A perpetuity refers to a future stream of cash flows, paying a constant amount regularly till forever. Such stream is never ending.
The present value of a perpetuity is computed by dividing the constant amount receivable till forever, by required rate of return/cost of capital.
Present value of a growing perpetuity is given by
= 
wherein cash flows represent cash flows receivable growing at g% rate till forever
r = required rate of return or cost of capital
g= growth rate of cash flows
Where the cash flows are of constant amount i.e non growing nature, the present value of such a perpetuity is given by,
= 