Screening of Enlisted Men in WWI

During the early 20th century, psychologists were tasked with developing a method to rapidly assess the cognitive abilities of a large, diverse population of military recruits. They created two distinct versions of an intelligence test: one that required reading and writing, and another that primarily used pictures and symbols. What is the most logical reason for this two-test approach?

During World War I, the U.S. military faced the challenge of rapidly processing and assigning roles to a massive influx of diverse recruits. Given this historical context, which statement best analyzes the fundamental problem that Robert Yerkes and his team of psychologists were tasked with solving?