下面算式中计算正确的是（　　）

A．100-20+80

=100-100

=0

B．（184+316）÷25×4

=500÷100

=5

C．1053-438-53

=1053-53-438

=1000-438

=562

D．2740-403

=2740-400+3

=2340+3

=2343

Thembi is a director of Okavango Ltd, but she also carries out her own business as a wholesale supplier of specialist metals under the name Savuti Ltd.Last year Okavango Ltd entered into a contract to buy a large consignment of metal from Savuti Ltd. Thembi attended the board meeting that approved the contract and voted in favour of it, without revealing any link with Savuti Ltd. The contract price was considerably above the market price and Savuti Ltd and Thembi made a considerable profit from it.Nevertheless the previous year was a particularly good year for Okavango Ltd and it was revealed at a board meeting on 20 March 2008 that it had made larger than expected profits.On learning this Thembi immediately bought more shares in Okavango Ltd, before the news of the profits was announced on 1 April.Required:Analyse the situation explaining any potential liability that Thembi may have in relation to:

(b) her purchase of the shares. (5 marks)