Which choice most logically completes the text? | Verbal SAT Question

Animal fossils from the Arabian Peninsula come primarily from two time periods and locations: a late Miocene (7.0-7.7 million years ago) site in the Baynunah Formation and a Pleistocene (12,000-500,000 years ago) site in the Nefud Desert. The 6.5-million-year gap between these fossil assemblages occurs in the context of considerable evidence of concurrent African-Eurasian faunal exchange. While limited exchange may have occurred via island hopping across the 5.3-million-year-old Mediterranean Sea, many of the species that moved between the continents were adapted to grasslands that could not have existed in sufficient size on Mediterranean islands, leaving only the peninsula as a viable exchange route, a fact suggesting that

Which choice most logically completes the text?

the gap in the fossil record between 7.0 million years ago and 500,000 years ago could be reflective of poor preservation conditions in the Arabian Peninsula at that time, inadequate fossil recovery efforts, or both.

even though grasslands likely flourished on the Arabian Peninsula between 7.0 million years ago and 500,000 years ago, the peninsula was not the only route by which grassland-adapted animals traveled between Africa and Eurasia.

conditions in the Arabian Peninsula were likely more conducive to fossilization before 7.7 million years ago and after 500,000 years ago than they were in the intervening period.

the absence of any evidence for African-Eurasian faunal exchange between 7.7 million years ago and 500,000 years ago should not be taken as evidence that the Arabian Peninsula formed a barrier to such exchange