A – Wrong
The passage only states that a brain-friendly lifestyle can help to retain more synapses but it does not state that a poor lifestyle causes loss of synapses.
B – Correct
The passage clearly states that in sentence 5. “…a brain-friendly lifestyle…extra synapses” suggests that elderly people who have lived a ‘brain-friendly’ lifestyle are expected to have higher number of synapses.
C – Wrong
This irrelevant to the text. The passage mainly focuses on the correlation of a ‘brain-friendly’ lifestyle in young age and number of synapses in old age. It does not mainly focus on the little understanding of deteriorating cognitive performance.
D – Wrong
The word ‘ensure’ is a too strong. Yes, the passage links reading, socialising and staying healthy with good life in old age but it does not ‘ensure’ it.
E – Wrong
This is just completely wrong and irrelevant.