"En bloc" is a French term that has been adopted into English. It means to do something as a whole or collectively, without breaking it into smaller parts. When something is done "en bloc," it is treated as a single unit or entity. This usage reflects the meaning of "collectively," which indicates that multiple elements or entities are acting together or being considered as a whole.

 The other options, such as "remarkably," "immediately," and "separately," do not convey the same sense of collective or unified action that "en bloc" does.