I am pretty sure the answer is D (combination)
When climbing a mountain, we can observe transitions in biological communities that are analogous to the changes in biomes at different latitudes.
<span>On a modern firearm, the feature that functions like the lock on a muzzleloader is the safety. The safety was added to modern guns to prevent them from accidentally firing, although it should be noted that a safety is a man-made mechanical device which makes it subject to failure at times.</span>
Rate of reaction will increase with the presence of a catalyst.
This is due to catalysts providing an alternative reaction pathway with lowered activation energy required, allowing an increased rate of reaction.
In meiosis, the homologues separate in anaphase I and the sister chromatids separate in anaphase II.