Which of the Following Is Not True Regarding ¹H NMR $\sigma$

Which of the following is not true regarding ¹H NMR spectroscopy?

A) "shielding" leads to peaks at lower values of $\sigma$
B) a "downfield" peak appears at a higher value of $\sigma$
C) " $\sigma$ for a particular proton depends on the magnetic field strength of the instrument used."
D) on a 300 MHz instrument, a proton that adsorbs irradiation at a frequency 1200 Hz higher than the adsorption of TMS appears at $\sigma$ 4 ppm.