Answer:
The correct answer would be d. thymus.
The thymus is a specialized lymphoid organ of an immune system.
It serves as the site for training and maturation of T-lymphocytes or T cells.
It is composed two identical lobes each containing outer region termed as cortex and inner region termed as medulla.
T-cells are first trained and selected in the cortex region via positive selection. In this, T cells which are able to bind to foreign antigens are selected and rest are degraded.
The selected T cells then move in the medulla region where they are selected by negative selection. In this, the T cells which binds to self-antigens are degraded and rest survive to become functional T cells.
In a heliocentric system, earth revolves around the sun.
Binary fission<span> and </span>mitosis<span> are both asexual forms of cellular reproduction that duplicate the existing DNA in a mother cell and split the cell into two exact copies called daughter cells. Eukaryotes use </span>mitosis<span> to reproduce the nucleus.</span>
A snow gauge is a form of technology, similar to the rain gauge which measures rainfall, that could be used to <em>monitor </em><span><em>and measure the amount of solid precipitation</em></span><span><em> (snow) over a set period of time.
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<em />I hope this helped!! :D Have a blessed day!<em>
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