A – Wrong
The text does not assume that people who have poor memory cannot become taxi drivers.
B – Wrong
This is clearly wrong as the text does not mention anything about people believing it is easy to becom a taxi driver.
C – Correct
The line “so all that learning…also increases their memory power” suggests that memory power increases after they have learnt the road network of London. IF the same group of prop were to undergo brain scans before they learnt, then the same results would not have been observed.
D – Wrong
Nothing mentioned in the text about why people choose to become taxi drivers.