Scid is defined by a lack of functional b and t cells which eliminates protection by humoral and cell-mediated immunity. Which of the following is true?
1) Scid is a condition characterized by an overactive immune system.
2) Scid is a condition caused by a deficiency in b and t cells.
3) Scid is a condition that enhances humoral and cell-mediated immunity.
4) Scid is a condition that does not affect the immune system.