in the linear regression model y = b1*x1 + b2*x2 + b3*x3

a negative b3 with a p-value below 0.05 would indicate:

That a lower x3 is associated with a higher y, with at least 95% confidence

That a higher x3 is associated with a higher y, with at least 95% confidence

That a higher x3 is associated with a higher y, with at least 5% confidence

That a lower x3 is associated with a higher y, with at least 5% confidence