Which theory explains the force powerful enough to send gigantic plates sliding around the earth? a. seafloor spreading b. subduction c. convection d. continental drift

One of the brightest comets of the 20th century was comet hyakutake, which passed close to the sun in early 1996. the orbital period of this comet is estimated to be about 30,000 years. find the semi-major axis of this comet’s orbit. compare it to the average sun-pluto distance and to the distance to alpha centauri, the nearest star to the sun, which is 4.3 light-years distant.

The great scientist alfred wegener proposed that continents have moved, while other scientists such as t.c.chamberlin argued against wegener. wegener's ideas eventually won, and are now widely accepted, because: a) wegener's ideas were more beautiful, and so were favored by the intellectual elite.b) wegener's ideas did a better job of predicting the results of new observations and experiments.c) wegener's ideas appealed to dead white european males, whereas chamberlin's didn't.d) wegener's ideas appalled dead white european males, and we all know that in this politically correct era,dead white european males cannot get a fair shake.e) wegener won the nobel prize.

Ecologist: the scottish highlands were once the site of extensive forests, but these forests have mostly disappeared and been replaced by peat bogs. the common view is that the highlands’ deforestation was caused by human activity, especially agriculture. however, [agriculture began in the highlands less than 2,000 years ago]. peat bogs, which consist of compressed decayed vegetable matter, build up by only about one footper 1,000 years and, [throughout the highlands, remains of trees in peat bogs are almost all at depths great than four feet]. since climate changes that occurred between 7,000 and 4,000 years ago favored the development of peat bogs rather than the survival of forests, the deforestation was more likely the result of natural processes than of human activity.in the ecologist’s argument the two portions in [parenthesis] play which of the following roles? a. the first is evidence that has been used in support of a position that the ecologist rejects; the second is a finding that the ecologist uses to counter that evidence.b. the first is evidence that, in light of the evidence provided in the second, serves as grounds for the ecologist’s rejection of a certain position.c. the first is a position that the ecologist rejects; the second is evidence that has been used in support of that position.d. the first is a position that the ecologist rejects; the second provides evidence in support of that rejection.e. the first is a position for which the ecologist argues; the second provides evidence to support that position.