Need some help! (TOEIC grammar questions)

[stefano77]

Hello everybody! Im gonna do TOEIC in just two weeks and I'm scared. I need some help with these questions. Sorry if they were already made.

Because of the firm's incompetent approach to the project, the customer has decided to terminate the business ________.

a. relation
b. relative
c. relatively
d. relationship
(I chose a, which is incorrect :s)

Due to the ________ demand for our new extrapolation system software, we will need to ensure satisfactory residue stock levels..

a. expectant
b. expected
c. expecting
d. expectorant
(I chose c)

Investors are advised to not merely rely upon the gossip ___________ industry specialists, but should also make their own personal analysis.

a. in
b. about
c. on
d. among
(I chose c)

It is fair to say that ________ such an increase in sales has never occurred in any sustained way, we should not ignore any possible impact it may have on our production ability and lead times.

a. when
b. that
c. which
d. although
(a)

The rich Invest __________ the poor do not must certainly be a sign of a class ability system.

a. in spite of
b. in that
c. where
d. which
(c)

Please explain me your answers! Thank you!