Identifying Correct Usage in Research Sentences

Identify the sentence that correctly applies the rules of standard English conventions of usage in the following scenario:

Research studies on cognitive development have shown that a variety of factors influences childhood learning. While some aspects, such as socioeconomic status, can be quantified, others, like emotional support, are more difficult to measure. However, any study intended to explore the comprehensive impacts of these variables would need to be methodologically rigorous to produce reliable results.

Which of the following sentences correctly addresses an error in standard English conventions?