Answer:
C). An athlete who did not receive much attention until after his death, sports historians and fans now admire Roberto Clemente's contributions to baseball.
Step-by-step explanation:
As per the question, option C displays the sentence that employs a modifier appropriately as the 'relative or adjective clause' that is modifying the noun 'an athlete' is appropriately placed next to the noun(as per the rules) it is describing along with a comma(,) after it to display the shift from the modifier to the basic idea of the sentence. Therefore, option C is the correct answer as the essential relative clause or modifier 'who did not receive much attention until after his death' that is defining the noun 'athlete' is appropriately placed in it. The other options either do not involve a modifier or fail to modify the noun it intends to modify/describe.