Final answer:
The primary disadvantage of using email as a primary communication tool in an organization is the potential for security breaches, which can result in data leaks and loss of privacy. These risks, along with the possibility of decreased efficiency due to email overload, can hinder effective communication within a company.
Step-by-step explanation:
Among the potential disadvantages of using email as a primary communication tool in an organization include: a) Security breaches, due to the risk of unauthorized access to sensitive information, which could result in data leaks and exposure to identity theft. The loss of privacy is another significant concern, as there is potential for increased surveillance and ease of information sharing could expose personal data. Furthermore, email can lead to d) Decreased efficiency, as the volume of messages can be overwhelming, making it difficult to prioritize and manage important communications effectively.
However, responding to the multiple-choice question provided, one could argue that in contrast to the options available, option b) Increased privacy and c) Improved collaboration are more likely to be viewed as benefits rather than disadvantages of email communication. Therefore the correct answer as per the question's context is a) Security breaches.