He is working under such . . . . . . conditions that it is difficult to maintain his self-respect.

The correct answer is: D. humiliating

The other options are:

• A. low: This option is not correct because it does not accurately describe the conditions that the person is working under. The conditions are not simply low, but they are humiliating.
• B. difficult: This option is not correct because it does not accurately describe the conditions that the person is working under. The conditions are not simply difficult, but they are humiliating.
• C. inimical: This option is not correct because it does not accurately describe the conditions that the person is working under. The conditions are not simply inimical, but they are humiliating.

The word “humiliating” means “causing someone to feel ashamed or embarrassed.” In this case, the person is working under conditions that are so bad that they are causing him to feel ashamed and embarrassed. This is why the correct answer is D. humiliating.