Because there are children in africa starving... Duhhh!!!!!
The Renaissance began in Italy partly because Italian city-states were wealthy. The answer to your question is A. I hope this is the answer that you are looking for and it comes to your help.
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The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory (1991–2000), the Chandra X-ray Observatory (1999–present), and the Spitzer Space Telescope (2003–2020). The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft.
Answer: Ligand gated channel
Explanation:
Ligand gated channel is an essential membrane protein that has pores and allows the passage of specific ions across the plasma membrane when it is activated by a specific chemical . Examples of such ions that pass through Ligand gated channels are Sodium ions, Potassium ions, Calcium ions. Ligand gated channels are found in extensions of the nerve cells.