The spherical bacteria that cause diseases such as pneumonia are:

The term for the spherical bacteria that can cause diseases like pneumonia is indeed associated with the correct answer. Spherical bacteria are classified as cocci, and when they occur in pairs, they are specifically referred to as diplococci. The genus Streptococcus, which is a type of diplococcus, often causes pneumonia and other infections.

While other types of bacteria listed, such as bacilli (which are rod-shaped) and spirilla (which are spiral-shaped), represent different classifications and have their own related diseases, they do not specifically pertain to the spherical shape of the bacteria responsible for pneumonia. Understanding these classifications helps in accurately identifying pathogenic bacteria and their respective diseases, making this knowledge crucial in areas such as health and microbiology.