Is there like options in this question?
This is an effective strategy because different phases do not compete for food.
For example for the case of Jelly fish, After a brief period floating about in surface waters like planktons, the larvae then settles to the sea floor, attaching themselves to one end. They then develop to polyps and begin to feed and grow. In spring the polyps bud iff immature jellyfish known as ephyra larvae which then grow to mature jellyfish.
C. Tree roots split apart rocks in the ground
It seems that you have missed to include the necessary options for this question so I had to look for it. Here is the answer. The one that lymphoid cells traps antigens and transport them to lymph nodes are the T LYMPHOCYTES. Hope this answers your question.