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.

answer and explanation;

volcanic rocks are igneous rocks which form from lava, molten rock which has been thrust out of a volcano onto the surface of a rocky body such as an asteroid, planet, or dwarf planet.  

plutonic rocks are igneous rocks which form from subterranean chambers of molten rock or magma. plutonic rocks make up the base of continental crust as well as oceanic crust. their slow rate of formation causes them to be coarse grained since there is plenty of time for large crystals to form before the magma solidifies into rock.

the textural difference is that plutonic rocks are more coarse grained than volcanic rocks. plutonic rocks are coarse grained while volcanic are fine grained ; glassey or fragmental. since fine and coarse are adjectives the decision as to whether a rock is fine or coarse grained is generally made on the bases of whether or not the individual crystals can be seen in most if the rock.