Final answer:
The term that matches 'weakness' is 'incapacity,' but in the context of the US party system, 'The inability to mobilize voters' opinions' is a current weakness.
Step-by-step explanation:
The question 'Which of the following matches the word "weakness"? a) incapacity b) irresolution c) impotence d) powerlessness' corresponds to options that are synonymous with the term 'weakness'. While all options have some connotation of deficiency, the best match for 'weakness' is 'incapacity' because it similarly implies a lack of ability or strength.
However, when referring to weaknesses within the context of the US party system, a notable current weakness is a. The inability to mobilize voters' opinions, which signifies challenges parties face in influencing and reflecting the political will of the electorate. Despite all of these choices relating to a lack of strength or ability, we must consider the context to choose the most appropriate term.