Which sentence shows a flaw or mistake in logic?

a volcanic eruption in the early 1800s threw so much ash into the air that it caused a global temperature dip.
sunspot activity affects earth's climate, which means that human activity is not a factor.
ice reflects more heat away from the earth than open water, which absorbs heat when it is exposed to the sun.
ocean currents, such as the gulf stream and the labrador current, have a significant effect on local climates.

Based on context, the word “insoluble”most likely means?

How can the passage best be revised to eliminate logical fallacies and improve clarity

Select the correct answer. in this excerpt from "a modest proposal" by johnathan swift, what does the author list? i can think of no one objection, that will possibly be raised against this proposal, unless it should be urged, that the number of people will be thereby much lessened in the kingdom. this i freely own, and 'twas indeed one principal design in offering it to the world. i desire the reader will observe, that i calculate my remedy for this one individual kingdom of ireland, and for no other that ever was, is, or, i think, ever can be upon earth. therefore let no man talk to me of other expedients: of taxing our absentees at five shillings a pound: of using neither cloaths, nor houshold furniture, except what is of our own growth and manufacture: of utterly rejecting the materials and instruments that promote foreign luxury: of curing the expensiveness of pride, vanity, idleness, and gaming in our women: of introducing a vein of parsimony, prudence and temperance: of learning to love our country, wherein we differ even from laplanders, and the inhabitants of topinamboo: of quitting our animosities and factions, nor acting any longer like the jews, who were murdering one another at the very moment their city was taken: of being a little cautious not to sell our country and consciences for nothing: of teaching landlords to have at least one degree of mercy towards their tenants. lastly, of putting a spirit of honesty, industry, and skill into our shop-keepers, who, if a resolution could now be taken to buy only our native goods, would immediately unite to cheat and exact upon us in the price, the measure, and the goodness, nor could ever yet be brought to make one fair proposal of just dealing, though often and earnestly invited to it. a. reforms that had failed to improve ireland's situation b. the unrealistic measures discussed by irish government officials c. viable measures that could improve ireland's situation d. measures that would unify the populace of ireland