Step #1 when approaching a science passage

Aboy with an extra x chromosome probably has which of the following syndromes?

Some birds look for food near cattle and other livestock. the movement of the cattle churns up the ground, making insects available to the birds. the cattle appear to be unaffected by the presence of the birds. what kind of relationship exists between the birds and the cattle? o a. parasitism o b. commensalism o c. predation o d. mutualism

Which event would lead to primary succession of a forest?