A plant's first line of defense against infection is
A)Avr genes.
B)its epidermis.
C)R genes.
D)salicylic acid.

Question

Quizplus · Accepted Answer

The epidermis of a plant is its outermost layer of cells and acts as a physical barrier against potential pathogens. It is the first line of defense that a plant has against infection.

Other options: 
A) Avr genes are actually pathogen genes that trigger plant defenses when detected by R genes. 
C) R genes are part of a plant's immune response, but they are not the first line of defense. 
D) Salicylic acid is a hormone that is produced by plants in response to infection, but it is not the first line of defense.

A Plant's First Line of Defense Against Infection Is