$"$In the next two to three decades, barring dramatic advances in geriatric

medicine, shortage of health workers will loom large in "aging

vulnerable$*$ countries. The US in particular will need at "least twice as

many physicians specializing in geriatrics as its current $9000,$ as well as

half a million more nurses by $2020."$

The above statement is an example of which type of trend?

Social

Technological

Economic

Ecological