Answer : Option B
Explanation :
Some nouns which are made of two or more words or nouns are known as compound nouns. For example, toothpaste is a compound noun which is made of two different nouns tooth and paste. Other examples include haircut, bedroom, sister-in-law, daughter-in-law, passer-by and more.
The plural of such nouns is obtained by adding's' to the main or the root/principal word. For example, daughters-in-law, passers-by, sisters-in-law, etc. So, replace 'brother-in-laws' with 'brothers-in-law' in this sentence.