Answer: Ethylene.
Ethylene is also an important natural plant hormone, and is used in agriculture to force the ripening of fruits, and also is naturally occurring (but not in such high amounts such as the ones you see on store shelves -- these are forced to ripen quickly compared to naturally occurring levels (which has low levels of ethylene at a time in comparison of forced ripening which has increased levels of ethylene at once).
Ethylene it is what causes a maturing apple to go red, and then that red apple starts to wither, get squishy/ soft, and then it starts to rot.
Answer:
(b) Volcanic eruptions
Explanation:
Volcanic eruption is naturally occurring event. In Volcanic eruptions many toxic gases are released into the atmosphere such as carbondioxide, carbonmonoxide, hydrogen sulfide, hydrochloric acid and Sulphur dioxide etc. These toxic gases goes to the atmosphere and combine with water vapours forming the water acidic. When this acidic water comes to the earth surface, skin and valuable stones are damaged from it.
There are two types of agricultural crop residues<span>. </span>Field residues<span> are materials left in an agricultural field or </span>orchard<span> after the crop has been </span>harvested. These residues include stalks and stubble (stems<span>), </span>leaves<span>, and </span>seed<span> pods. The residue can be ploughed directly into the ground, or </span>burned<span> first. Good management of field residues can increase efficiency of </span>irrigation<span> and control of </span>erosion<span>. </span>Process residues<span> are materials left after the crop is processed into a usable resource. These residues include </span>husks<span>, seeds, </span>bagasse<span>, </span>molasses<span> and </span>roots<span>. They can be used as animal </span>fodder<span> and </span>soil amendment<span>, fertilizers and in </span>manufacturing<span>.</span>
Autotrophic organisms, also known as plants and certain protists, perform photosynthesis. Hope this helps! :)