Answer:
b. your marginal tax rate
Step-by-step explanation:
When deciding whether to accept the additional work the most important tax factor in your decision is your marginal tax rate.
The marginal tax rate is the percentage of tax on an individual's income for each tax bracket above a pre-defined cash-flow threshold.
Basically, marginal rates measure the degree to which an individual would be willing to accept more risk in additional work or investment portfolios.