Sat simple question!

Thanks a lot!

How should the syntax in this sentence be changed, if at all? the scientists spent years analyzing the results of numerous medical studies meant to identify the cause of the disease. no change the scientists spent years looking at the results of a variety of different medical studies meant to locate the cause of the disease. the scientists spent years reviewing medical study results to find the cause of the disease. the scientists spent years studying the results of many medical studies in order to uncover the cause of the disease.

D/dx(1+x^4+x^6/x^2+x+1) a)2x-1 b)2x+1 c)2 d)0

To the north of ginnungagap it was bitterly cold. (20) nothing was there but fields of snow and mountains made of ice. to the south of ginnungagap was a region where frost and snow were never seen. it was always bright, and was the home of light and heat. the sunshine from the south melted the ice mountains of the north so that they toppled over and fell into ginnungagap. there may be a mistake in the way the sentence is written. if you find a mistake, choose the answer that corrects the mistake. if there is no mistake, choose ‘correct as is.' a) correct as is. b) nothing was there but snow fields and mountains of ice. c) nothing was there but fields of snow and icey mountains. d) nothing was there but fields of snow and mountains of ice.