"what basic problem is reflected in the communication difficulties and impaired social relationships of asd children? "

The basic problem reflected in the communication difficulties and impaired social relationships of ASD children is that the mutual give and take of normal, or typical communication and interaction is specially challenging for children with ASD.  This results in their impossibility to play  with other children, they may fail to respond to their name, they cannot understand their own feelings or other people's feelings, therefore, they cannot talk about their own feelings.  Their speech can often be awkward and inappropriate.

they all focused on themes about the inevitability of death.

i truly dont know the answer wait i do its 1,3,4