What rule applies to this word?

envy
a. group i. if the root is a full word, the ending is usually -able.
b. group ii. when the root is a full word except for a final e, the forms usually are spelled with -able
c. group iii. the suffix -able always follows i.
d. group iv. when the root has other forms built on the letter a, the -able form is used
e. group v. when the root ends in hard c or hard g, -able is used.
f. group vi. when the root is not a full word,-ible is used.
g. group vii. when the word has an immediate -tion form, -ible is used.
h. group viii. when the root ends in ns, miss, or soft c or g, ible is used.