How exactly should you (what does it mean to) use appropriate eye contact, adequate volume, and clear pronunciation?

To keep eye contact and not to look away like your ignoring them

Eye Contact:

Look at them, and not like you're ignoring them.

Adequate Volume:

Satisfying volume, as in you hear them, and not some other talking, and making sure that you only hear them.

Clear Pronunciation:

Talking clearly, and not all slurred.

Example:

"I luh-ikee you too"

The correct answer is B) like Harbur, many were shocked by stock market collapse and ensuing Depression.

Harbur’s words reflect the experience many Americans had during the Great Depression in that like Harbur, many were shocked by stock market collapse and ensuing Depression.

The words from Harburg in the excerpt expressed the idea that prosperity would last forever, was a given, and nobody expected the opposite. Then the stock market crashed and that was a shock to the American people that never dreamt of an event like that. Harburg said “If you made it it was there forever. Suddenly the big dream exploded.” That is how Harburg literally refers to the shock they felt when they knew about the market collapse.  

The other options of the question were, a) like Harbur, many expected they could maintain their possessions during the Depression, c) like Harbur, many were grateful for the lessons they learned, and d) like Harbur, many made meticulous plans to prepare for the Depression.