In the field of astrobiology, scientists study the light passing through the atmospheres of distant exoplanets to search for signs of life. The detection of key chemical biosignatures, such as seasonal variations in methane concentrations combined with high levels of oxygen, _______ the presence of active biological processes rather than abiotic chemical reactions.
Which choice completes the text so that it conforms to the conventions of Standard English?
- Aindicate
- indicatesCevap
- Cindicating
- Dhave indicated
Cevap
indicates
The subject of the sentence is the singular noun 'detection.' The intervening prepositional phrase 'of key chemical biosignatures' and the parenthetical example 'such as seasonal variations...' contain plural nouns ('biosignatures,' 'variations,' 'concentrations,' 'levels'), but they do not change the number of the subject. Therefore, the verb must be singular. The singular, present-tense verb 'indicates' correctly agrees with the singular subject 'detection.'
Adım Adım Çözüm
Anahtar Kavram
Subject-Verb Agreement