How would you specify in your build.gradle file that your app required at least API level 21 to run, but that it can be tested on API level 28?
 A
      defaultConfig {
        ...
        minApiVersion 21
        targetApiVersion 28
      }
 B
      defaultConfig {
        ...
        targetSdkVersion 21
        testSdkVersion 28
      }
 C
      defaultConfig {
        ...
        minSdkVersion 21
        testApiVersion 28
      }
 D
      defaultConfig {
        ...
      minSdkVersion 21
        targetSdkVersion 28
      }