It sounds like you're referring to the "Law of Cause and Effect," which tells us that every material effect has a prior cause. I counter that your question is an example of special pleading, suggesting that everything requires a cause, except for this super special uncaused cause which started everything.
Either every "cause requires a cause" or "not every cause requires a cause." Either all causes were caused by a prior event, meaning the uni-multi-ultraverse model you propose is perpetual, or not every cause requires a prior cause which means there is no need for a special snowflake "initial cause" needing to "choose" to start things off.
Anyway, modern science (and the Law of Cause and Effect) only offer models for how reality operates in our present universe. As such, it does not (necessarily) apply before our universe existed, and may not have even applied during the initial moments after the big bang.
Our scientific models of the universe do not speak to how things worked before the big bang, and currently the only thing we know about things before planck time are that things certainly did NOT operate according to the same rules (http://hyperphysics.phy-astr.gsu.edu/hbase/astro/planck.html).