The correct option is C Today, the leisure hours of a child are spent in front of the TV.
The sentence implies that a child spends his leisure hours in front of a TV. Therefore the subject is "the leisure hours" which has "of a child"a s its adjunct". The verb is "are spent" and the object is " the TV" joined by the preposition "in front of". Hence, Option C is correct. The rest of the options do not adhere to this logical sequence, hence incorrect.