Question

Choose the correct possessive form.

"I couldn't marry him," said Debra. "I wouldn't be able to tolerate my two _____ attitudes."

sisters'-in-law
sister's-in-law
sisters-in-law's
sisters-in-laws'

Answer 1

D) Sisters-in-laws'
The reasoning for this is because when a noun that is possessive is plural, the apostrophe is placed after the "s". When a noun that is possessive is singular, the apostrophe is then placed before the "s".

Answer 2

The correct answer is 
D. Sisters-in-laws'