Of the following parents giving praise to their child, which is using the most effective strategy? ...

Of the following parents giving praise to their child, which is using the most effective strategy?
 
  a. Abdul tells his daughter, You're a good girl when she is polite to the neighbor.
  b. Barney tells his son, I'm so proud of how well you prepared for your biology test..
  c. Cornelius uses the phrase, You did a wonderful job every time he praises his daughter.
  d. Darnell says to his son, I'm proud of how you played tennis, but maybe next time you'll get more points..
  e. Ed, who after his daughter shows him her artwork, avoids making eye contact but says, That's a great job you did..