For f(x)=lnx on [1,4], the magnitude of the second derivative satisfies ∣f′′(x)∣≤1 for all x in the interval. What is the least even integer n(n≥2) such that an approximation of ∫14lnxdx using n equal-width trapezoids is guaranteed to have an error less than 0.001?
a) 32
b) 60
c) 48
d) 24