A common practice in project cost risk simulation is to estimate the total project cost by adding up individual work package (WP) costs. Under the __________________ assumption, there can be "random" canceling out between the WPs underrunning their budgets and those over-running their budgets. This canceling-out behavior may lead to a significant underestimation of the true project cost risk. a) independence (WP costs are independent) b) negative correlation c) dependence (WP costs are correlated) d) None of the others e) positive correlation