Dual Enrollment Earth Science Practice Test 2026 - Free Earth Science Practice Questions and Study Guide

The main idea is recognizing certainty in the author’s language. The author uses definitive wording to state that El Niño and La Niña events will continue to occur, which is a clear, future-focused certainty about the ENSO cycle.

This is the only statement that asserts something guaranteed to happen. The other lines describe general traits or predictions that aren’t presented as definite guarantees: weather being highly variable is a broad characteristic of weather in general; global temperatures rising is a forecast that can be influenced by many factors and isn’t claimed as an absolute certainty here; and saying El Niño never ends conflicts with the well-established, cyclical nature of ENSO and isn’t a plausible claim of certainty.