In which of the following IDS evasion techniques does an attacker deliver data in multiple small sized packets, which makes it very difficult for an IDS to detect the attack signatures of such attacks

Insertion attacks cause the IDS to accept and process extra packets that the target host will actually reject (due to TTL expiry or checksum errors), inflating the IDS's view of the stream to confuse signature matching.

Fragmentation overlap sends IP fragments with overlapping offsets so that the IDS and target host reassemble conflicting byte sequences, exploiting differences in overlap resolution logic rather than using small packet sizes.

Fragmentation overwrite is a variant of overlap where later fragments intentionally overwrite earlier ones during reassembly to alter what the end host processes, distinct from the small-packet splitting strategy of session splicing.

Session splicing exploits the fact that many IDS engines have a minimum viable packet size or reassembly timeout threshold - by delivering attack data in abnormally small TCP segments (sometimes as small as 1 byte per segment), the attacker ensures the signature is never present in any single packet the IDS inspects. The target host's TCP stack reassembles the full payload and processes the complete attack while the IDS never triggers on the fragmented stream.