In second marriages, couples are older and tend to be
a. more realistic
b. more romantic
c. less cautious
d. less flexible

correct option is a.  more realistic

Explanation:

we know that marriage is legally relationship between a husband and a wife

and some for of marriage are

1 Arranged marriage

2 Civil marriage

3 Common law marriage

4 Boston marriage

5 Berdache marriage

and in second marriage

age and experience will be more

so as they age, they have gained experience from their past life

so we can say that in second marriages old couples tend to be more realistic

so correct option is a.  more realistic

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

substitution is the answer in this case