Ok-so I've been riding for 40 years, and teaching and training for 20. I have always based a horses' jump on his athletic abilities, scopiness, etc. I've seen the solid, 2'6 packers that can stretch to 3' but are better suited to the 2'6 job.
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Vitamin A is an essential, fat-soluble vitamin that has many diverse benefits for humans. It promotes eye health and helps you see in the dark; aids in the differentiation of cells of the skin (lining the outside of the body) and mucous membranes (linings inside of the body); helps the body fight off infection and support the immune system; and, supports growth and remodeling of bone.