The most direct and dramatic response to a union-management negotiation deadlock that the union can make is a:

A) primary boycott
B) work slowdown
C) lockout
D) strike
E) secondary boycott

A strike is the most direct and dramatic response to a union-management negotiation deadlock because it involves workers refusing to work and can have a significant impact on the company's productivity and profitability. This can put pressure on management to negotiate and come to an agreement with the union. A primary boycott may also be effective, but it involves the public refusing to use the company's products or services, which may not be as directly impactful as a strike. A work slowdown may also be an option, but it is less dramatic and may not have as much of a financial impact on the company. A lockout is initiated by management, not the union, and involves the company shutting down operations and preventing workers from entering the workplace, which is not a response that the union can make. A secondary boycott is also not a direct response that the union can make, as it involves targeting a company's customers or suppliers rather than the company itself.