B – said. ‘It is said’ is the most common passive voice structure here that has the meaning of something that is more or less common knowledge.
D – up. ‘To keep somebody up’ means to leave somebody without sleep, to keep somebody awake.
B – try. ‘To give a try’ is to test, try or taste something to see whether you like it or not or whether it is good enough. ‘To give somebody a chance’ has a different meaning – to provide an opportunity to do or show something. Options A and D do not collocate at all.
C – roasting. This one is more tricky as it is specific to coffee – you roast the beans, not fry or cook them.
D – number. ‘A number of’ is a set phrase with the meaning ‘some, several’. Other options here do not make a set phrase.
B – proven. What science does is proves(among other things) certain theory or hypotheses. Options A and C don’t make any collocations. Option D would work in a slightly different context: ‘… scientifically advised to do something/that you do something…’
C – to. ‘Limit’ is the verb you should be looking at. It is important to understand the difference between ‘limit to/by’. The first means what is actually limited (‘Passengers are limited to 30 pounds of luggage each’), while the second is the thing or person the limit is imposed by (‘Such actions are limited by the government’).
A – cause. To cause means to be the reason of something. ‘Result’ can be used with a similar meaning, however it should take a different preposition: ‘to result in something’.