The discrimination method is that the second derivative is less than 0.
because
(2^x)''=(2^x)(ln2)^2>； 0
(log_2x)''=- 1/(x^2ln2)<； 0
(x^2)''=2>； 0
Choose B.
figure
Here's the thing: like a broken line? Disappear into the sea of people?
23 15? 3323-7 1?
I finally lost my eyes? Your face?
23 15432?