[单选题]
A monatomic gas is cooled by 50 K at constant9qsmevbg*gx2n ch s h;q5:6p8 volume when 8plcg/r:x2m 7x+o/my b31 J of energy is removed from it. How7y2:m m/ +/bx rpgcxol many moles of gas are in the sample?
A. $2.50 \; mol$
B. $1.50 \; mol$
C. $1.33 \; mol$
D. none of the above
