The correct option is D all the above
There are several mechanisms within the seed that induce dormancy in seeds. Sometimes, the seed coat is impermeable to water and oxygen. Since a seed needs water and oxygen for germination, an impermeable seed coat leads to dormancy. When a seed coat is too hard, the embryo can't germinate.
Some chemicals present inside the seed can also cause dormancy. Chemical inhibitors like abscisic acid and phenolic acids prevent the seed's germination.
Some plants release their seeds before the embryo has fully matured. The seed remains dormant until the embryo matures completely.
Hence, an impermeable seed coat, a hard seed coat, chemical inhibitors or even an immature embryos can give rise to dormancy in a seed.