If the above statements are facts, which of the following can be logically inferred?

Question

Fact 1: Humans are mammals.                                                 

 Fact 2: Some humans are engineers

 Fact 3: Engineers build houses

If the above statements are facts, which of the following can be logically inferred?

1. All mammals build houses
2. Engineers are mammals.
3. Some humans are not engineers

      (a) II only                                                           (b) III only

      (c) I, II and III                                                     (d) I only