It Is Thought That the Earth's Climate Is Being Changed

question 60

Multiple Choice

It is thought that the Earth's climate is being changed rapidly by ________.

• A) human-caused releases of impurities
• B) increased oxygen content
• C) natural sources of change
• D) dust from volcanoes
• E) decreases in carbon dioxide

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Definitions:

Antigen Presenting Cells

Immune system cells that process and present antigens to T-cells, initiating an immune response.

Cytotoxic Cells

Immune cells that can kill cancer cells or cells infected with viruses by inducing apoptosis.

CD8

A protein found on the surface of T cells, involved in the immune response by identifying and attacking infected or cancerous cells.

Progenitor

An ancestor or parent from which descendants or offspring arise.