21- My brother __ a basketball player when he was young. am b) was c) 0 were d)( O is e) O are Bos birak

## Step 1<br />The sentence is in the past tense, as indicated by the phrase "when he was young". This means that the verb we need to use should also be in the past tense.<br />## Step 2<br />The verb "to be" in the past tense is "was" or "were". However, "was" is used for singular subjects, while "were" is used for plural subjects.<br />## Step 3<br />In this sentence, the subject is "my brother", which is a singular subject. Therefore, we should use "was" instead of "were".<br />## Step 4<br />The options "am", "is", and "are" are in the present tense and do not fit the context of the sentence.<br />## Step 5<br />Therefore, the correct answer is "was".