His depressing attitude became a cause of trouble for us all.

Answer: Option B

Depressing : causing or resulting in a feeling of miserable dejection.
Horrifying : causing horror; extremely shocking.
Uplifting : morally or spiritually elevating; inspiring happiness or hope.
Bewildering : confusing or perplexing.
Digressing : leave the main subject temporarily in speech or writing.

Antonym of Depressing is Uplifting