44. These results show ____ the mice in the treatment group healed more quickly than the control mice. (A) which (B) what (C) this (D) that

40. Scientists say feral pigeons are a valuable way of probing contaminants in environment, ___ they are exposed to the same air, water, food and other factors as humans, and don’t venture far from home. (A) although (B) hence (C) because of (D) since