Read the following passage and mark the letter (A, B, C or D) on your answer sheet to indicate the correct answer to each for the questions.
During the late Middle Ages, oil paint took hold as the artistic medium of choice because it was effective, flexible, and resilient relative to the wax-based, watercolor, fresco, or tempera paints prevalent at the time. Although contemporary commercially prepared paints contain a mixture of pigments and linseed oil, poppy oil paints are also available to connoisseurs. The original recipes developed in medieval European monasteries relies on fast-drying bases derived from various organic oils predominantly valued for their medicinal qualities. The pigments are insoluble, lightproof, and chemically inert powders ground in the base. Occasionally, varnish can be added to increase the paste’s ability to reflect light and to cover pictures with a protective seal. The resulting stiff, resinous compounds are often packaged in flexible metal or plastic tubes. Historically, yellow pigments have been added to the oil, and then the paste was layered over tin foil to imitate the appearance of gold leaf.
Despite the numerous experiments to accelerate the drying process, oil paints dry comparatively slowly with little color alteration. An important advantage of color stability is that tones and undertones are easy to blend, match, transpose, and grade, and mistakes and smudges are simple to correct. Due to the creamy consistency of most mixtures, artists can exploit their viscosity in thick applications, sprays, thin trickles, and three-dimensional blobs. The purification by boiling and filtering and bleaching of oils can impart varied hues to powdered pigments, while drying time can be reduced by adding metallic oxides. Professional painters who mix their own medium usually have their own trademark methods of mixing materials that art experts recognize as a part of an artist’s creative work.
The thickness of the paste also plays an important role in defining the stages of painting a picture. After the basic design is sketched in pencil or charcoal, the broad background or foreground areas of the canvas are covered with thin, diluted paint on top of the primer. A thicker paint, often with added varnish, is subsequently used to refine and outline the foundation. The width of the brush depends on the type of paint the artist chooses to use, and stiff bristles are usually found in narrow brushes for making sharp lines, while softer brushes of animal hair can be employed in broad strokes.
According to the passage, medieval monks extracted oil
A.from minerals
B.in conjunction with pigments
C.from plants
D.in combination with medicines
