The sentence on letter b is the correct answer. Unlike all the errors found in letter a (Zacks' instead of Zack's), letter c (families' instead of families), and letter d (Its instead of It's), letter b a perfect thought without any errors in its punctuation marks.
Dear Uncle (name), your generosity is much appreciated. Thank you for giving me a new laptop you know how much I wanted one and needed one. Thank you for helping me.
