The correct option is
C what
Idiomatic expressions have a meaning different from the literal meanings of the individual words.
Option C: 'What' forms an expression 'and what not' which means 'and other things, and so forth'. The meaning fits into the sentence, that states all the things that the television contains.
Hence option C is correct.
Options A, B and D: 'Which, 'who' and 'whose' do not form idiomatic expressions.
Moreover, 'who' and 'whose' generally refer to people, and not things.
Hence, the meaning formed is not the same as the meaning formed in literal words.
So, options A, B and D are wrong.