For the first question, it is B since xylem does not have living cells and instead have dead cells unlike phloem. The other answers are correct since it carries and transports water and dissolved minerals and has thick cell walls with a hallow lumen.
For the second question, I am not exactly sure but it might be A since it promotes cell division and mitosis is a type of cell division. You might wanna double check that one, though.
The type of mutation that causes this translation error is called deletion. Deletion occurs when a section of a DNA is deleted or lost. In cystic fibrosis, three nucleotides are deleted that results in the lost of phenylalanine
