Question

In recent decades, season creep ________, which means that many phenological signs of spring are occurring earlier in many regions by a couple of days per decade. А) has been observed Б) has observed В) was observed Г) is observed

Answer 1

А) has been observed

Answer 2

The correct option is А) has been observed.

"In recent decades, season creep has been observed, which means that many phenological signs of spring are occurring earlier in many regions by a couple of days per decade."

The phrase "has been observed" is in the present perfect tense, which is suitable for describing an action or phenomenon that started in the past and continues into the present. In this case, season creep is an ongoing phenomenon that has been observed over recent decades.