Which principle of development is illustrated in the following statement?…

Developmental psychology recognises several principles that govern how children grow, one of which is the sensitive (or critical) period principle: certain abilities, most notably language, develop most readily during a defined early-life window, and being deprived of the right environmental input during that window causes lasting difficulty picking up the ability later, even after the window has closed.

The statement describes exactly this pattern: children who lack a conducive language-learning environment in their early years struggle to pick up language later in life. That link between early-years deprivation and lasting later difficulty is the defining signature of a sensitive period for language development, not a general claim about genetics, cognition, or randomness.

• "Development of language is totally dependent on genetics" makes acquisition purely inborn, but the statement's cause is an environmental factor (a deprived learning environment), which a purely genetic account cannot explain.

• "Language and cognition are complexly interrelated" describes a general relationship between two mental domains; the statement instead is about a time-bound window for acquiring language, not about language's link to cognition.

• "Development is disorderly and unpredictable" claims development follows no fixed pattern; the statement instead describes a specific, predictable early-years window, the opposite of disorderliness.

Because the scenario turns on a bounded early window whose loss cannot be fully compensated for later, it illustrates the principle that there is a sensitive period of language development.