I have / two sister-in-laws / whose husbands / are all well settled.
A
I have
B
two sister-in-laws
C
whose husbands
D
are all well settled
E
No Error
Correct Answer: two sister-in-laws
Change, sister-in-laws → sisters-in-law. Plural of such compound words is formed by adding 's' in the first constituent of the compound word.