Final answer:
The correct sentence is 'Mick Jagger, who is over sixty-five years old, draws huge crowds,' as it uses an adjective subordinate clause to join the two sentences.
Step-by-step explanation:
The correct way to join the sentences is by using an adjective subordinate clause that modifies the noun 'Mick Jagger.' Of the options provided, the sentence that accurately combines the two original sentences using an adjective subordinate clause is:
a) Mick Jagger, who is over sixty-five years old, draws huge crowds.
This sentence uses 'who is over sixty-five years old' as an adjective clause to describe Mick Jagger. It correctly relates the fact that despite his age, Mick Jagger is able to draw large audiences to his performances.