Correct Option: A

As we can say that ,
‘Education is central’ is highlighting the importance and role, electronic networks and software-driven technologies have. The sentence has a positive connotation. Option (a) is correct, because ‘break down’ refers to ‘falling apart or collapsing, or failure to function’ and the barriers are physical or metaphorical walls which hinder free movement, hence, this is the appropriate word. Option (b) is wrong, because ‘break’ refers to ‘destroying the integrity of ’ or ‘get ruined’, but as we are talking about ‘barrier’, ‘break down’ is more appropriate.Option (c) is wrong, because crumble means ‘break into pieces’. Option (d) is wrong, because dismantle can be considered synonymous with crumble.
The correct word is filled in the above given sentence :-
Education is central because electronic networks and software-driven technologies are beginning to break down the economic barriers between nations.