Fill in the blanks: Our body, when it encounters a pathogen for the first time, produces a response called . . . . . . $a$ . . . . . . response, which is of . . . . . . $b$ . . . . . . intensity. Subsequent encounters with the same pathogen elicit a . . . . . . $c$ . . . . . . intensified . . . . . . $d$ . . . . . . response.

• A
  $a-$Anamnestic, $b-$Low, $c-$High, $d-$Secondary
• B
  $a-$Secondary, $b-$High, $c-$Low, $d-$Primary
• C
  $a-$Primary, $b-$Low, $c-$High, $d-$Anamnestic
• D
  $a-$Primary, $b-$High, $c-$Low, $d-$Anamnestic