Question

the behavior of eusocial insects, such as ants and termites, continues to fascinate evolutionary biologists due to its complex social structure. research ____ that sterile worker castes increase colony fitness across multiple species and ecological contexts suggests that kin selection plays a central role in their evolution, though recent field studies have also highlighted the influence of ecological constraints—such as nest defensibility and resource distribution—in shaping how and when eusocial systems emerge.
17
which choice completes the text so that it conforms to the conventions of standard english?
(answer : d)
a demonstrates
b has demonstrated
c are demonstrating
d demonstrating

Explanation:

To determine the correct verb form, we analyze the sentence structure. The main verb of the sentence is "suggests", so the underlined part should be a non - finite verb (participle) acting as an adjective to modify "Research".

• Option A: "demonstrates" is a finite verb (present simple). If we use it, the sentence will have two main verbs ("demonstrates" and "suggests") without proper conjunction, which is grammatically incorrect.
• Option B: "has demonstrated" is a finite verb (present perfect). Similar to option A, using it will result in a sentence with two main verbs, which is wrong.
• Option C: "are demonstrating" is a finite verb (present continuous). "Research" is a singular noun, and "are" is used for plural subjects, so this is also incorrect.
• Option D: "demonstrating" is a present participle. It functions as an adjective to modify "Research", indicating the characteristic of the research (that it demonstrates...). This fits the sentence structure and grammar rules.

Answer:

D. demonstrating