I found the attached image on the internet related to this question.
The solid arrows represent neuronal communication. The stimulus, the effects, and the flow of information is all done by receptors and synapses that send a signals across the body in order to have effective feedback responses promoting the homeostasis of the organism.
 
        
        
        
This process is called Denitrification. The process is undertaken by the denitrifying bacteria, whose action is converting nitrates in the soil to free atmospheric nitrogen and therefore, depleting soil fertility and reducing agricultural productivity. Examples of denitrifying bacteria are thiobacillus denitrificans, micrococcus denitrificans among others.
        
             
        
        
        
Answer:
periosteum ----> dense irregular connective tissue
Explanation:
- The periosteum is a dense fibrous membrane that covers the surfaces of bones. 
The periosteum consists of two layers-
     1. Outer fibrous layer 
     2. Inner cellular layer
- It is mainly composed of dense irregular connective tissue along with a layer of simple squamous epithelium.
- The function of periosteum is to cover the surface of all the bones except those surfaces that are covered with cartilage such as joints and tendons and ligaments. 
 
        
             
        
        
        
Answer:
B. Hardness
Explanation:
Physical properties of a substance is defined as the properties which can be observed or measured without changing the composition of matter. 
Physical properties include odor, appearance, color, texture, boiling point, melting point and many others.
Hardness is a physical property of a substance as it describes the  resistance of substance to deformation and can be observed by simple touch or without changing the composition of matter.
While reactivity, toxicity and flammability are chemical properties of substances that change one type of matter into another type.
Hence, the correct option is B.