Question: What primary wine acid is found naturally in citris fruits?

Context paragraphs:
Ethyl lactate: Ethyl lactate, also known as lactic acid ethyl ester, is a monobasic ester formed from lactic acid and ethanol, commonly used as a solvent.  This compound is considered biodegradable and can be used as a water-rinsible degreaser.  Ethyl lactate is found naturally in small quantities in a wide variety of foods including wine, chicken, and various fruits.  The odor of ethyl lactate when dilute is mild, buttery, creamy, with hints of fruit and coconut.

Hexanoic acid: Hexanoic acid (caproic acid) is the carboxylic acid derived from hexane with the molecular formula CHCOOH.  It is a colorless oily liquid with an odor that is fatty, cheesy, waxy, and like that of goats or other barnyard animals.  It is a fatty acid found naturally in various animal fats and oils, and is one of the chemicals that give the decomposing fleshy seed coat of the ginkgo its characteristic unpleasant odor.  It is also one of the components of vanilla.  The primary use of hexanoic acid is in the manufacture of its esters for artificial flavors, and in the manufacture of hexyl derivatives, such as hexylphenols.

Methyl cinnamate: Methyl cinnamate is the methyl ester of cinnamic acid and is a white or transparent solid with a strong, aromatic odor.  It is found naturally in a variety of plants, including in fruits, like strawberry, and some culinary spices, such as Sichuan pepper and some varieties of basil. " Eucalyptus olida" has the highest known concentrations of methyl cinnamate (98%) with a 2–6% fresh weight yield in the leaf and twigs.

Sarcosine: Sarcosine, also known as "N"-methylglycine, is an intermediate and byproduct in glycine synthesis and degradation.  Sarcosine is metabolized to glycine by the enzyme sarcosine dehydrogenase, while glycine-"N"-methyl transferase generates sarcosine from glycine.  Sarcosine is an amino acid derivative that is naturally found in muscles and other body tissues.  In the laboratory, it may be synthesized from chloroacetic acid and methylamine.  Sarcosine is found naturally as an intermediate in the metabolism of choline to glycine.  Sarcosine is sweet to the taste and dissolves in water.  It is used in manufacturing biodegradable surfactants and toothpastes as well as in other applications.

Wine lactone: Wine lactone is a pleasant smelling compound found naturally in apples, orange juice, grapefruit juice, orange essential oil, clementine peel oil and various grape wines.  It was first discovered as an essential oil metabolite in Koala urine by Southwell in 1975.  It was discovered several years later by Guth in white wines and was named "wine lactone".  This monoterpene imparts "coconut, woody and sweet" odors to a wine.  There are 8 possible isomers of wine lactone with the (3"S", 3a "S", 7a"R") isomer being the only one that has been found in wine.  This isomer is also the most potent of all eight with an odor detection threshold of 10 ng/L in model wine.

Citric acid: Citric acid is a weak organic tricarboxylic acid having the chemical formula CHO.  It occurs naturally in citrus fruits.  In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms.

Acids in wine: The acids in wine are an important component in both winemaking and the finished product of wine.  They are present in both grapes and wine, having direct influences on the color, balance and taste of the wine as well as the growth and vitality of yeast during fermentation and protecting the wine from bacteria.  The measure of the amount of acidity in wine is known as the “titratable acidity” or “total acidity”, which refers to the test that yields the total of all acids present, while strength of acidity is measured according to pH, with most wines having a pH between 2.9 and 3.9.  Generally, the lower the pH, the higher the acidity in the wine.  However, there is no direct connection between total acidity and pH (it is possible to find wines with a high pH for wine and high acidity).  In wine tasting, the term “acidity” refers to the fresh, tart and sour attributes of the wine which are evaluated in relation to how well the acidity balances out the sweetness and bitter components of the wine such as tannins.  Three primary acids are found in wine grapes: tartaric, malic and citric acids.  During the course of winemaking and in the finished wines, acetic, butyric, lactic and succinic acids can play significant roles.  Most of the acids involved with wine are fixed acids with the notable exception of acetic acid, mostly found in vinegar, which is volatile and can contribute to the wine fault known as volatile acidity.  Sometimes, additional acids, such as ascorbic, sorbic and sulfurous acids, are used in winemaking.

Tergallic acid: Tergallic acids are trimers of gallic acid, often found naturally in the form of glycosides. Tergallic acid O- or C-glucosides that can be found in acorns of several "Quercus" (oak) species.  The dehydrated tergallic acid C-glucoside and tergallic acid O-glucoside can be characterised in the acorns of "Quercus macrocarpa".  Dehydrated tergallic-C-glucoside (m/z 613) can be found in the cork from "Quercus suber".

Valeric acid: Valeric acid, or pentanoic acid, is a straight-chain alkyl carboxylic acid with the chemical formula CHO.  Like other low-molecular-weight carboxylic acids, it has a very unpleasant odor.  It is found naturally in the perennial flowering plant valerian ("Valeriana officinalis"), from which it gets its name.  Its primary use is in the synthesis of its esters. Volatile esters of valeric acid tend to have pleasant odors and are used in perfumes and cosmetics.  Ethyl valerate and pentyl valerate are used as food additives because of their fruity flavors.

Caprylic acid: Caprylic acid is the common name for the eight-carbon saturated fatty acid known by the systematic name octanoic acid.  Its compounds are found naturally in the milk of various mammals, and as a minor constituent of coconut oil and palm kernel oil.  It is an oily liquid that is minimally soluble in water with a slightly unpleasant rancid-like smell and taste.

Supporting paragraphs: Acids in wine Citric acid
Answer: Citric acid