The method of directly injecting sperm into ovum in Assisted Reproductive Technology is called:

GIFT – Gamete Intra Fallopian Transfer is one of the methods of Assisted Reproductive Technology (ART). GIFT is the process of transferring an ovum collected from a donor into the fallopian tube of another female who cannot produce an ovum but can provide a suitable internal environment for fertilisation. So option (a) is incorrect.

ZIFT – Zygote Intra Fallopian Transfer is another method of Assisted Reproductive Technology. In ZIFT the zygote or early embryos (with up to 8 blastomeres) is transferred into the fallopian tube to complete its further development. So option (b) is incorrect.

ICSI – Intra Cytoplasmic Sperm Injection is one of the specialised procedures to form an embryo in the laboratory in which a sperm is directly injected into the ovum.

ET – Embryo Transfer is transferring embryo using various methods or techniques.

So the method of directly injecting sperm into ovum in Assisted Reproductive Technology is called ICSI.

Hence the correct answer is option (c).