Read the statements given below with respect to disease-causing microbes.
a. All parasites are pathogens as they cause harm to the host.
b. Pathogens have to adapt to life within the environment of the host.
c. Pathogen of dysentery lives in the gut of host organism.
d. Pathogens can enter human body by various means causing functional damage but do not interferes with normal vital activities.
Select the option that contains correct statements:
1. (a) and (b) only
2. (b) and (c) only
3. (a), (b) and (d) only
4. (a), (b), (c) and (d)