In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

[EX Q]: The enzyme LCAT catalyzes the formation of an ester from this compound. Intermediates in the synthesis of this compound include squalene [SKWAY-leen] and mevalonate [muh-VAL-uh-nate], the latter of which is produced by HMG-CoA reductase. Vitamin D is formed from the 7-dehydro form of this compound, which reduces membrane fluidity. This compound, which is transported to the liver by high-density lipoprotein, is linked to heart disease. For 10 points, name this compound whose amount in the blood is lowered by statins such as Crestor and Lipitor.
[EX A]: Science

[EX Q]: Mobility is related to the zeta potential, dielectric constant, and this quantity in the Smoluchowski equation. For gases, the variation of this quantity with temperature is given by Sutherland's formula. Measured with a Zahn cup, this quantity is squared in the Grashof number, and the ratio of this quantity to thermal diffusivity is the Prandtl number. When this quantity is zero, the Euler equations correspond to the NavierStokes equations. Reynolds number is the ratio of inertial forces to this quantity, which is constant for Newtonian fluids. Measured in poise [PWAHZ], this quantity is zero for superfluids. For 10 points, name this internal friction of a fluid that tends to resist its flow.
[EX A]: Science

[EX Q]: Synthetic varieties of this mineral were made by Auguste Verneuil using the flame-fusion process. Asterism in this mineral is caused by the inclusion of rutile. One variety of this mineral has a shade known as Kashmir blue, and another variety has a shade called pigeon's blood. The material emery consists of magnetite and this mineral. Aluminum oxide occurs naturally in large deposits as this mineral, which has a value of nine on the Mohs scale of hardness. For 10 points, name this mineral whose transparent varieties, such as sapphire and ruby, are used as gems.
[EX A]:
Science