Answer: it is c, a covalent bond
Explanation:
 
        
             
        
        
        
Implantation is the major sign of pregnancy for various women, it is a stage in which a zygote of fertilized egg limplants into the wall of the uterus. 
Implantation usually takes place 6 to 10 days post ovulation, or day 20 to 24 of a menstrual cycle. However, it can take place a few days later or earlier. Once fertilization takes place, the egg remains the fallopian tuve for three days prior of getting inside the uterus and starts to implant itself to the walls of the uterus. 
 
        
             
        
        
        
The scientific term for the formation of a new species is speciation. So, the correct answer would be letter d. :)
        
             
        
        
        
Answer:
valence electrons an element has in its outer shell, the easier it is to complete.
The most electron shells an element has, the easier it is to fill its outermost shell.
Explanation:
Non metals atoms bond to other elements by sharing or completing the valance electrons in other element. This is easily made when the other element lacks a small number of electrons, for example with Hydrogen it has 1 valance electron because of that it is easier to bond with other elements.
 
        
             
        
        
        
the electron transport chain is responsible for generating the most ATP within cellular respiration. The electron transport chain is responsible for generating the most ATP within cellular respiration. This answer has been confirmed as correct and helpful.