"Effect" refers to the result or outcome of a particular cause.
The opposite of "effect" is "cause," which refers to the reason or origin of something.
"Educ" (1) is related to drawing out or bringing forth, which does not directly oppose "effect."
"Sidle" (3) means to move sideways, often secretly or furtively, and is unrelated to "effect."
"Redact" (4) means to edit or prepare written content, particularly for public release, and does not relate to the concept of "effect."
Conclusion:
The opposite of "effect" is "cause," as it refers to the origin of an event or result.