The process of using a series of parallel lines set close to one another to differentiate planes of value in a work of art is called

Hatching The process of using a series of parallel lines set close to one another to differentiate planes of value in a work of art is called .

Explanation:

All right, so, even though it might look unreal the name of this technique is called "hatching". But Hatching is the technique to shade, give effects or style a figure by using close parallel lines to structure the image. There is also another type of hatching but is not parallel and because in this case, we needed parallel we just call it hatching. It is widely used in Asian works and one of it's most popular usage is to give effects to manga a type of Japanese comic. they are all made in different media but purists produce them only in ink to make it more challenging and difficult.  

the answer is d . a measurement   how can artists measure the width of the human face to use drawing for correct proportions

b.) a 3-d model