Question

tracking migratory counts along the east asian - australasian flyway ___ essential for evaluating shorebird decline. the annual census coordinated by the australasian wader studies group documents population changes across 23 monitored wetlands. in 2021, surveys at the yellow sea recorded a 34 percent decrease in calidris tenuirostris compared with 2005 baselines.
20
mark for review
which choice completes the text so that it conforms to the conventions of standard english?
a are
b were
c is
d have been

Explanation:

The subject of the sentence is "Tracking migratory counts...", which is a gerund phrase acting as a singular subject. So the verb should be singular. Also, the context (documenting population changes, surveys in 2021) suggests a general truth or current importance, so present tense is appropriate. "is" is singular and present tense, matching the subject and context.

Answer:

C. is