How many dihalogen derivatives of propane are there?

The compound with the formula C₄H₉Br has how many structural isomers?

(CH₃)₃CCH₂CH(Br)C₆H₅ is 

1. Secondary benzyl halide

2. Secondary alkyl halide

3. Primary alkyl halide

4. Secondary allyl halide

CH₃CH₂CH(CH₃)CH(C₂H₅)Cl is:

1. Secondary benzyl halide

2. Secondary alkyl halide

3. Primary alkyl halide

4. Secondary allyl halide

CH₃CH₂C(CH₃)₂CH₂I  is:

1. Secondary benzyl halide

2. Secondary alkyl halide

3. Primary alkyl halide

4. Secondary allyl halide

(CH₃)₂CHCH(Cl)CH₃ can be classified as:

1. Secondary benzyl halide

2. Secondary alkyl halide

3. Primary alkyl halide

4. Secondary allyl halide