One of the Interesting Findings of a Survey of Firm

One of the interesting findings of a survey of firm managers by Blinder et al.is that:

A) the vast majority of firms pay considerable attention to marginal costs in making decisions about how much output to produce.
B) the majority of respondents suggested that fixed costs are a relatively unimportant consideration when making output decisions.
C) approximately 75 percent of respondents indicated that their marginal costs of production are rising over the relevant range of output.
D) a significant percentage of respondents to the survey did not appear to understand the concept of marginal cost.