Please help, im on a time limit
Antibodies are a Y-shaped protein that are secreted by the immune system to identify and neutralize pathogens in vertebrates. Antibodies have an antigen binding site that allows for binding to surface proteins found on a specific pathogen, called antigens. All cells have identifying protein markers on the surface that specify whether it’s foreign or a part of the same organism. Some pathogens have the ability to alter their antigens, preventing antibodies from identifying them.
Which of the following arguments is BEST supported by this information?


A
The shape of an antigen allows for antibodies to identify the cell, indicating that the shape of the protein provides specificity.
B
The binding site of an antibody can be altered to accommodate more pathogens.
C
Antibodies must be a complex protein because it is only found in vertebrates.
D
Pathogens can release their own antibodies to fight off host immune system.