'A $ B' means 'A is the sister of B',

'A @ B' means 'A is the daughter of B',

'A * B' means 'A is the father of B' and

'A - B' means 'A is the son of B'.

Based on the above information, which of the following means that D is the daughter's husband of M?​​​​

The family trees for the given expressions in the options are as follows:

So, from the above, D is M's daughter's husband.

​So, from the above, D is M's daughter's husband's sister.

​So, from the above, D is M's father's sister's son's daughter.

So, from the above, D is M's daughter.

Thus, the correct answer is (a).​​