DNA sequencing has been performed for how many of these organisms?
Caenorhabditis elegans, Drosophila , Arabidopsis, Homo sapiens.

The correct option is D 4
The Human Genome Project was launched in 1990 with the aim to sequence the entire human genome. A genomic sequence comprises information of all the nucleotides that form the genes.

Hence, DNA sequencing, that is obtaining the entire genomic sequence of an organism has been done for humans (Homo sapiens). However, it has also been done for many organisms such as bacteria, yeast, Caenorhabditis elegans (a free-living non-pathogenic nematode), Drosophila (the fruit fly), plants like rice and Arabidopsis.