WHAT'S BLACK BOX UNIT TESTING ?

Question

I recently had my final exam for a software engineering course for my masters program and one of the questions on the exam was the following:

Unit Testing is considered: a. White-box Testing b. Black-box Testing c. Either

Answer 1

Unit testing falls under WHITE box testing. Unit testing is a testing of units class of the codes. So, we need to look into the codes for the unit testing. whereas the black box testing is a testing of overall application.

Answer 2

black box testing is for testing features through providing input and checking output, but without any knowledge of implementation.
technically you can do some black box testing at unit test level, but unit test should usually include some white box testing.