Although all the three fields have equal number of opportunities and it is quite debatable that which out of the three is highly lucrative because there are people in all the three domains who have earning high. However, if earning is your only concern then any of these three fields would suffice the purpose. It would be more prudent on your part to identify your passion and expectations, this will help you go a long way in any domain because these days if you would read about the industry trends the number of people quitting their jobs due to frustration is quite high, the job satisfaction parameter has considerably gone down, a main reason for the same is that people chose something which they found more lucrative rather than something they might have found more interesting.

So try to read more on these subjects and identify a domain which interests you the most as each one of these subjects have great career prospects.