Which of the following is a byproduct of hydrogenation of vegetable oils?

Trans fatty acids are isomers of cis fatty acids which are found in naturally occurring unsaturated fatty acids. They are formed during hydrogenation of vegetable oils in the production of margarine. The configuration of groups in a trans fatty acid is such that the acyl chains are on the opposite side of the double bond. Trans fatty acids not only raise the level of triglycerides, total and LDL cholesterol but also lower the level of HDL. Hence their consumption is associated with an increased risk of cardiovascular disease. The WHO recommends that the intake of trans fats should be less than 1% of the total energy intake. Reference: Harpers illustrated biochemistry 30th edition page 213