Question

A strong economy depends on many investors speculating. many banks giving many people loans. most consumers buying on credit. most people’s confidence in the economy.

Answer 1

A strong economy depends on "most people’s confidence in the economy," since it is this consumer confidence that allows banks to make loans and people to pay back these loans in a responsible fashion. 

Answer 2

In short to HistoryGuy's answer A strong economy depends on most people’s confidence in the economy which is letter D