, then only the first sentence is right. Even though the next sentence is correctly easy to understand, it ought to be written as an alternative as follows: Aus Sicherheitsgründen, hat er sich entschieden es nicht zu tun. The which means of “seit” is the fact that something has begun https://titusiqwbg.wikistatement.com/3992659/bachelorarbeit_schreiben_lassen_an_overview