Which sentence is the best addition to improve his analysis

Biologists recognize five levels of cell organization. the lowest and simplest is the cellular level. organisms here are either unicellular organisms, like protozoa, or colonial organisms. colonial organisms are composed of single-celled individuals that stay together to sustain the life of the whole colony. next on the scale of complexity is the level occupied by tissue. a tissue is a group of similar cells which perform a similar activity. tissues that are organized around a common function together make up an organ, the third level of complexity. the fourth level of organization is the system, formed by a group of organs which together perform a specific bodily process. the fifth and highest level is the organism level, in which body systems work together in a structure capable of independent life. main idea:

Which lines from the speech best supports this topic sentence? and as we walk, we must make the pledge that we shall always march ahead. we cannot turn back. there are those who are asking the devotees of civil rights, "when will you be satisfied? " and they have come to realize that their freedom is inextricably bound to our freedom. we cannot walk alone. we refuse to believe that there are insufficient funds in the great vaults of opportunity of this nation. and so we've come to cash this check, a check that will give us upon demand the riches of freedom and the security of justice. and so let freedom ring from the prodigious hilltops of new hampshire. let freedom ring from the mighty mountains of new york. let freedom ring from the heightening alleghenies of pennsylvania.

Why are reading and writing necessary in today’s world