Which of the following is true about the challenges of client-side marketing plans:
a. Marketing plans are complex, costly, and time-consuming to produce
b. A small business may not have money or the skilled management to produce a professional plan.
c. In fast-changing market, a plan could become out of date before it's published.
d. Marketing managers may become 'wedded' to a plan to which they have devoted so much time and energy.
e. All of the above