When a kettle is placed on the stove and water begins to boil, the hotter water at the bottom begins to rise and the cooler water above it begins to sink. What type of heat transfer does this situation represent? Thermal Conduction Radiation Convection

If the water vapor content stays the same and the temperature drops, then the relative humidity increases. its vise versa.if the water vapor content stats the same and the temperature rises, the relative humidity decreases. so, yes, i'd say that temperature and humidity have a strong relationship.

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.

The chemical bubbles

The air is going to come out because of the low pressure.