A family of mother, father, daughter, son and his wife pose for a photograph occupying sequential positions A, B, C, D and E in a line. Spouses are next to each other and the daughter is next to her mother.
If E is occupied by the son, which of the following is necessarily true?

Correct option is B

Given:
Family members: Father, Mother, Daughter, Son, Son’s Wife
Positions: A, B, C, D, E (left to right, in line)
Spouses are next to each other
So: (Father-Mother) and (Son-Son’s Wife) must be adjacent.
Daughter is next to her mother
E is occupied by the Son

Solution:

Fix:
Son at E
His wife must be at D (since only adjacent position available)
So:

A B C D       E
_ _ _  Wife  Son

Now, we have A, B, C left for:
Father
Mother
Daughter
And with the conditions:
Mother-Father must be adjacent
Mother-Daughter must be adjacent
Can Mother be at B?
Try:
A = Father
B = Mother
C = Daughter
Father and Mother are adjacent
Mother and Daughter are adjacent

Final arrangement:

A      B               C             D       E
F    Mother  Daughter  Wife   Son

​This fits all constraints.
Spouses next to each other:
Father & Mother → A & B
Son & Wife → D & E
Daughter next to Mother → C & B

Final Answer: (B) B is occupied by the mother