For humans, lactic acid fermentation occurs when you exert yourself to the point that your muscles can no longer get oxygen fast enough to generate energy via aerobic respiration. When this happens, your muscles produce energy by the far less efficient process of lactic acid fermentation. This is also true in most other mammals In bacteria, however lactic acid fermentation can either be the normal method that a bacteria has for producing energy, or it can be a method used when there is no oxygen available. Which of these will be the case depends on the type of bacteria.
The first answer is correct: "They suggest that the heat is stifling, giving the poem an oppressive mood".
The author begins the poem with the sentence cited above. The use of the expression "rend open" plus the use of the imperative mode, suggest some sort of desperation caused by the heat. That is why the author prays for wind (an unbeatable natural force) to come and defeat heat, ending the suffering.
A. by using it to introduce new characters and develop main characters!
Designer jeans are very expensive.