The unique subak water management system used to irrigate the rice paddy fields of the Indonesian island of Bali has a rich cultural, philosophical, and historical significance dating back to the ninth century. The many elements of subak—terraces, canals, and water temples—are ____: they are joined together into a single cohesive unit.

Which choice completes the text with the most logical and precise word or phrase?

The discoveries of natural satellites by Scott S. Sheppard’s team of astronomers have been ____: Carpo, which the group of researchers found orbiting Jupiter in 2003, is just one of over one hundred that they have spotted, while many astronomers have been happy to discover only one or two.

Which choice completes the text with the most logical and precise word or phrase?

Certain features are almost always included in the designs of mosques, like the ablution (ritual cleansing) area, which is considered to be a ____ of mosque architecture. Even mosques that exhibit elements of multiple architectural styles, such as the Al-Fattah Al-Aleem Mosque, which incorporates elements from the Islamic and Fatimid styles, will also include several of these standard features.

Which choice completes the text with the most logical and precise word or phrase?

____ traditional descriptions of pollination syndromes (suites of floral traits, such as nectar composition and scent bouquet, hypothesized to have independently evolved as a result of selection pressure exerted by pollinators) and recent empirical observations of floral-trait combinations have led some ecologists to express reservations about the utility of those descriptions.

Which choice completes the text with the most logical and precise word or phrase?

Vertical gene transfer involves the transmission of genetic material from a parent to offspring; horizontal gene transfer, on the other hand, involves the exchange of genetic material between organisms not in a parent-offspring relationship. While horizontal gene transfer is common among prokaryotes—single-celled organisms, such as the bacteria Brevundimonas diminuta and Lactobacillus curvatus—it has rarely been observed among eukaryotes (multicellular organisms). However, new studies suggest that horizontal gene transfer is more common in eukaryotes than originally thought.

Which choice best states the function of the underlined sentence in the text as a whole?