Used in many cleaning detergents and hygiene products to produce suds, a compound named Sodium Lauryl Sulfate (SLS), which was found to cause irritation of facial skin with prolonged exposure, was the subject of a famous Internet hoax in the 1990s.
A. Used in many cleaning detergents and hygiene products to produce suds, a compound named Sodium Lauryl Sulfate (SLS), which was found to cause irritation of facial skin with prolonged exposure, -> We have right modifiers used and non underlined part also connected with the current structure. Let's keep it.
B. A compound, which was found to cause irritation of facial skin with prolonged exposure, named Sodium Lauryl Sulfate (SLS), and used in many cleaning detergents and hygiene products to produce suds, -> A compound named ....and used, was........this is not better than A. Let's drop it.
C. Used in many cleaning detergents and hygiene products to produce suds, found to cause irritation of facial skin with prolonged exposure, a compound named Sodium Lauryl Sulfate (SLS) -> Modifier error. Incorrect.
D. A compound that was found with prolonged exposure to cause irritation of facial skin and was used in many cleaning detergents and hygiene products to produce suds, named Sodium Lauryl Sulfate (SLS), -> "A compound that was found....." Incorrect.
E. A compound, which it was found to cause irritation of facial skin with prolonged exposure, named Sodium Lauryl Sulfate (SLS), used in many cleaning detergents and hygiene products to produce suds -> "it" is incorrect.
So, I think A.