This is decay. The exponent has a negative sign. The reciprocal of 2 is 0.5. So N(t) can be rewritten as 0.5ᵗ/⁸. The base is fraction less than 1, which is decay.
Check all facts you included in your answer.
O The negative exponent means that you must take the reciprocal of the base 2.
O The reciprocal of 2 is 0.5 (or ½).
O The base 0.5 (or ½) is less than 1.
O Bases less than 1 cause decay.