option A- by looking at country B, star cars market share was the same, but the amount of sales increase, meaning the total car market increased. Therefore it is not this answer.
option B- in 2010 star cars has 10% markets share and 10 mill cars. therefore there is 100 mill cars overall. in 2011, they have 12 mill cars and 12% market share, therefore there is still 100 mill cars overall. Therefore the total car market stayed the same, it did not increase.
option c - in 2010 Star markets market share for country B was at 10% at 10 mill, therefore there was 100 mill cars overall. In 2011, 10% = 12mill cars. Therefore there is now 120 mill cars in the total market share. This increased, therefore it is incorrect
option D - the market share obviously decreased from 10% to 6%. in 2010 10 mill =10%, therefore there was 100 mill cars in the total market. in 2011, 8 mill = 6% ..........therefore total car market = (100/6) x 8 =133.33 million cars in the total car market. Therefore the total car market increased. Therefore this is the correct answer. This would've tricked a lot of candidates.