The People of La Paz, Bolivia Can Grow Wheat and Barely

The people of La Paz, Bolivia can grow wheat and barely at an elevation of 4103 m (13,461 ft) because

A) the air is thicker than normal at their location and it therefore traps more heat energy-making the climate much warmer than would be expected based on its location.
B) La Paz is located fairly close to the equator.
C) daylength does not vary much at La Paz and this provides relatively uniform temperatures throughout the year.
D) of all of the above.
E) B and C only