At which dew point temperature would the amount of water vapor in the air be greatest

Dew point indicates the amount of moisture in the air. The higher the dew points, the higher the moisture content of the air at a given temperature. The temperature in which water vapor would be at  20 degrees Celsius or 68 degrees Fahrenheit. The Relative humidity is defined as the ratio of the partial pressure of water vapor to the saturated vapor pressure at a given temperature

Relative Humidity = partial pressure of H₂0/saturated vapor pressure of H₂0  Multiply by 100%

Example at 20⁰C = 17.5 torr

That would mean 120% Humidity

    5.5 n======    assuming that      we have      m = 0.145 kg    a = 38 m/s²therefore    5.51 n, but two significant figures.final answer: 5.5 n

The correct answer is  "c".  it is "c" because melting is an endothermic change, and endothermic get's energy from surroundings.