Two answers could be correct both B and D it does depend on the type of health work you are working in if you swim you burn calories and energy so being rested is a positive answer however by many health organizations or people in general 30 minutes is a safe time to swim after digestion, but if I was to say a more accurate answer would be B
Agreement or concord happens when a word changes form depending on the other words to which it relates. It is an instance of inflection, and usually involves making the value of some grammatical category "agree" between varied words or parts of the sentence.