When assigning costs, one of the challenges that audit firm, Lee, Indran and Partners $($LIP$)$ faces is the fact that some of the costs incurred cannot be easily traced to the audit engagements it undertakes. Which of the following solutions that are available to LIP with regard to these hard to trace costs would likely result in the most accurate assignment of cost to each of its audit engagements?

$1.$ Use an allocation base that reflects the audit engagement's ability to bear these costs

$2.$ Use an allocation base that is the cost driver of these hard to trace costs

$3.$ Allocate the indirect costs equally across all its audit engagements

Group of answer choices

Solution $1$

Solution $2$

Solution $3$