A rectangular channel having a bed slope of $0.0001$, width $3.0$ m and Manning’s coefficient   $’n’$ $0.015$, carries a discharge of $1.0 \: m^3/s$. Given that the normal depth of flow range between $0.76$ m and $0.8$ m. The minimum width of a throat (in m) that is possible at a given section, while ensuring that the prevailing normal depth is not exceeded along the reach upstream of the contraction, is approximately equal to (assume negligible losses)

1. $0.64$
2. $0.84$
3. $1.04$
4. $1.24$