Correct answer: D
A pollen is where male gametes are produced and so the number of chromosomes, as we are talking about gametes, is n. This means that the grain of pollen will only have a copy of each gene, and therefore only one allele for each gene - one S, and one T or t. So, the possible combinations are ST and St.
The nettle animals. Corals, sea anemones and jellyfish belong to a group of animals called cnidarians (pronounced 'nid-air-e-ans'). ... With 1,048 marine species, cnidarians are one of the largest groups of invertebrates in New Zealand waters.
It IS NOT A because after a fire, soil remains, so it would be secondary, not primary. D is INCORRECT because after a volcano, only rock is left so it is primary succession, not secondary.
If you can post the picture I could tell you the correct answer.