Before the BNS, "terrorist act" as a legal term lived mainly in special statutes; the question is testing where it now sits inside the general penal code.
Locating the actual terrorist-act definition points squarely to one section among the four.
\[ \boxed{\text{Section 113}} \]A quick way to answer this is to recall what each of the four cited sections of the BNS actually governs and see which one matches "terrorist act."
Matching subject matter to section number leaves only one candidate standing.
Hence, the correct answer is Section 113.