$1 \mathrm{~mm}$ of $\mathrm{Hg}$ pressure is equivalent to one torr and one torr is equivalent to $133.3 \mathrm{~N} / \mathrm{m}^{2}$. The atmospheric pressure in $\mathrm{mm}$ of $\mathrm{Hg}$ pressure is:
(a) $70 \cdot \mathrm{mm}$
(b) $760 \mathrm{~mm}$
(c) $3.76 \mathrm{~mm}$
(d) none of these