Answer:
All of them.
Explanation:
For considering the annuity formula we can determinate all the proposed factor:

C represent II the amount of each cash flow
r = represent the discopunt rate
while time or "n" represent the numebr of cashflow we have to calcualte the present value.
The timing refer wether the payment are made at the beginning or end of the period.
When made at the beginning it is an annuity-due
and the (1+r) factor multiplies the previous formula to represent the addtional period of capitalization each cashflow has or the one period less to discount for each cashflwo in cases of prresent value.
Answer:
Marilyn take a good decision.
Explanation:
Marilyn refuses to pay Carl because Marilyn did not sell any goods due to its bad quality so Marilyn earn no money and is unable to pay Carl. Marilyn will be able to pay Carl if the goods are sold and she has the money but when there is no sale at all, Marilyn is unable to pay for the goods on the due time. Marilyn should return the goods to Nigel instead of paying money for it because these goods are useless and nobody will it at all.
I think the answer must be True! Because the scientist are uncertain of how long the resources will be last. Hope it helped you! Have a great day! :)