Which of the following are best described as short chains of amino acids that are very stable and can have a variety of different antimicrobial activities, such as forming pores in bacterial plasma membranes and inhibiting cell wall synthesis?
a) siderophores
b) antimicrobial peptides
c) mannose-binding lectin
d) antiviral proteins

The right answer is c) Mannose Binding Lectins  

Which are known to be natural carbohydrate binding proteins and are highly specific to some sugar groups of other molecules.  

Explanation:

Lectins are widely distributed in nature and are isolated from various microorganism. lectins binds to sugar molecules on the microbial surface as potent antimicrobial agents. The Mannose (carbohydrate) binding lectins have the ability to form pores in the bacterial cell membrane which causes changes in the permeability of cells and will interact with cell wall components.  

"a.) well–developed vascular system."