occurs when the lower part of the neural tube fails to close. Conversely, occurs when the top part of the neural tube fails to close.

1. Spina bifida

2. Anencephaly

Explanation:

The neural tube is the structure formed in the growing embryo which forms the central nervous system which includes the brain and the spinal cord.

Due to some environmental factors like lack of folic acid and the multiple genes, the neural defect disorder occurs before birth.  The lower portion of the neural tube forms the spinal cord and the upper portion of the neural tube form the brain.

When the lower portion of the neural tube fails to grow than the spine does not grow properly and leads to the spina bifida.

When the upper portion of the neural tube fails to grow then some part of the skull, scalp and brain fail to grow which leads to a condition known as Anencephaly.

Thus, Spina bifida and Anencephaly are correct.

explanation:

the answer would be d