mocha test failed with unknown option -r

If I run TCs as "mocha -r .\test-scripts\mocha-setup.js .\test\test-ms.spec.js --exit ", I can run the TCs, but if I run as "mocha -r .\test-scripts\mocha-setup.js --exit ".\test\test-ms.spec.js, I get unknown option -r . Any idea why I get different behavior depends on where I pass --exit ?