- (Topic 3)
Instances of "galactic cannibalism"—mergers in which large galaxies completely consume smaller ones—may be fairly common. Tidal forces produced by the Milky Way's powerful gravity, for example, appear to be dismantling and engulfing a dwarf galaxy in the constellation Sagittarius, producing large clumps and streamers of stars connecting the two galaxies. Astronomers have also observed two dense clusters of stars and gas at the heart of the Andromeda galaxy, an apparent "double nucleus" that may contain the remnant of a cannibalized dwarf galaxy. But this twin-lobed appearance could also be created by two parts of a single nucleus bisected by a lane of dust. Scientists believe that only about 25 percent of such apparent double nuclei actually represent galactic cannibalism. Many of the rest result from the illusion of proximity that occurs when objects at different distances appear along the same line of sight: others consist of debris from galactic "collisions." in which one galaxy has passed through another without merging, causing waves of new star formation.
The primary purpose of the passage is to

Correct Answer:C

- (Topic 3)
The term "ragtime opera" was used frequently m the first years of the twentieth century, but more often than not its use was (i) _____ . The very idea of "ragtime opera" was viewed as lii) _____ : opera was regarded as the highest form of musical art; ragtime was at the opposite pole.

Correct Answer:B

- (Topic 2)
Exhibit.

Correct Answer:B

- (Topic 3)

Correct Answer:A

- (Topic 2)

In Country P the percent spent on outdoor advertising in 2012 was one-half of the corresponding percent spent in 2013. Which of the following is closest to the amount spent on outdoor advertising in Country P in 2012 ?

Correct Answer:A

- (Topic 3)
Larvae of many marine invertebrate species delay their metamorphosis into juveniles when cues signaling an appropriate juvenile environment are absent, thereby increasing then* likelihood of thriving as juveniles and of ultimately reaching adulthood Nevertheless, delayed metamorphosis has potential costs for juveniles including reduced growth and increased mortality Nearly all evidence of such costs involves species whose larvae do not feed but rather subsist on stored nutrients, indicating that insufficient energy reserves may be an underlying cause of these costs. Supporting this hypothesis are laboratory studies showing that in a certain bryozoan. the prolonged larval swimming that results from delayed metamorphosis is associated with size reductions in the juvenile feeding organ (the lophophore) and that one factor influencing the size of juveniles of certain barnacle species is how long larvae delay metamorphosis However, other studies show that while significantly fewer juvenile Capitella worms survived to adulthood when metamorphosis had been delayed, prolonged larval swimming had no significant effect on juvenile size, suggesting, perhaps, that in some species, factors other than insufficient energy reserves account for the negative effects of the larval stresses that result from delayed metamorphosis.
The "hypothesis" implies that compared to marine invertebrate larvae that subsist on stored nutrients, marine invertebrate larvae that feed are less likely to

Correct Answer:B